/*
* I2C adapter for the IMG Serial Control Bus (SCB) IP block.
*
* Copyright (C) 2009, 2010, 2012, 2014 Imagination Technologies Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* There are three ways that this I2C controller can be driven:
*
* - Raw control of the SDA and SCK signals.
*
* This corresponds to MODE_RAW, which takes control of the signals
* directly for a certain number of clock cycles (the INT_TIMING
* interrupt can be used for timing).
*
* - Atomic commands. A low level I2C symbol (such as generate
* start/stop/ack/nack bit, generate byte, receive byte, and receive
* ACK) is given to the hardware, with detection of completion by bits
* in the LINESTAT register.
*
* This mode of operation is used by MODE_ATOMIC, which uses an I2C
* state machine in the interrupt handler to compose/react to I2C
* transactions using atomic mode commands, and also by MODE_SEQUENCE,
* which emits a simple fixed sequence of atomic mode commands.
*
* Due to software control, the use of atomic commands usually results
* in suboptimal use of the bus, with gaps between the I2C symbols while
* the driver decides what to do next.
*
* - Automatic mode. A bus address, and whether to read/write is
* specified, and the hardware takes care of the I2C state machine,
* using a FIFO to send/receive bytes of data to an I2C slave. The
* driver just has to keep the FIFO drained or filled in response to the
* appropriate FIFO interrupts.
*
* This corresponds to MODE_AUTOMATIC, which manages the FIFOs and deals
* with control of repeated start bits between I2C messages.
*
* Use of automatic mode and the FIFO can make much more efficient use
* of the bus compared to individual atomic commands, with potentially
* no wasted time between I2C symbols or I2C messages.
*
* In most cases MODE_AUTOMATIC is used, however if any of the messages in
* a transaction are zero byte writes (e.g. used by i2cdetect for probing
* the bus), MODE_ATOMIC must be used since automatic mode is normally
* started by the writing of data into the FIFO.
*
* The other modes are used in specific circumstances where MODE_ATOMIC and
* MODE_AUTOMATIC aren't appropriate. MODE_RAW is used to implement a bus
* recovery routine. MODE_SEQUENCE is used to reset the bus and make sure
* it is in a sane state.
*
* Notice that the driver implements a timer-based timeout mechanism.
* The reason for this mechanism is to reduce the number of interrupts
* received in automatic mode.
*
* The driver would get a slave event and transaction done interrupts for
* each atomic mode command that gets completed. However, these events are
* not needed in automatic mode, becase those atomic mode commands are
* managed automatically by the hardware.
*
* In practice, normal I2C transactions will be complete well before you
* get the timer interrupt, as the timer is re-scheduled during FIFO
* maintenance and disabled after the transaction is complete.
*
* In this way normal automatic mode operation isn't impacted by
* unnecessary interrupts, but the exceptional abort condition can still be
* detected (with a slight delay).
*/
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/completion.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/timer.h>
/* Register offsets */
#define SCB_STATUS_REG 0x00
#define SCB_OVERRIDE_REG 0x04
#define SCB_READ_ADDR_REG 0x08
#define SCB_READ_COUNT_REG 0x0c
#define SCB_WRITE_ADDR_REG 0x10
#define SCB_READ_DATA_REG 0x14
#define SCB_WRITE_DATA_REG 0x18
#define SCB_FIFO_STATUS_REG 0x1c
#define SCB_CONTROL_SOFT_RESET 0x1f
#define SCB_CLK_SET_REG 0x3c
#define SCB_INT_STATUS_REG 0x40
#define SCB_INT_CLEAR_REG 0x44
#define SCB_INT_MASK_REG 0x48
#define SCB_CONTROL_REG 0x4c
#define SCB_TIME_TPL_REG 0x50
#define SCB_TIME_TPH_REG 0x54
#define SCB_TIME_TP2S_REG 0x58
#define SCB_TIME_TBI_REG 0x60
#define SCB_TIME_TSL_REG 0x64
#define SCB_TIME_TDL_REG 0x68
#define SCB_TIME_TSDL_REG 0x6c
#define SCB_TIME_TSDH_REG 0x70
#define SCB_READ_XADDR_REG 0x74
#define SCB_WRITE_XADDR_REG 0x78
#define SCB_WRITE_COUNT_REG 0x7c
#define SCB_CORE_REV_REG 0x80
#define SCB_TIME_TCKH_REG 0x84
#define SCB_TIME_TCKL_REG 0x88
#define SCB_FIFO_FLUSH_REG 0x8c
#define SCB_READ_FIFO_REG 0x94
#define SCB_CLEAR_REG 0x98
/* SCB_CONTROL_REG bits */
#define SCB_CONTROL_CLK_ENABLE 0x1e0
#define SCB_CONTROL_TRANSACTION_HALT 0x200
#define FIFO_READ_FULL BIT(0)
#define FIFO_READ_EMPTY BIT(1)
#define FIFO_WRITE_FULL BIT(2)
#define FIFO_WRITE_EMPTY BIT(3)
/* SCB_CLK_SET_REG bits */
#define SCB_FILT_DISABLE BIT(31)
#define SCB_FILT_BYPASS BIT(30)
#define SCB_FILT_INC_MASK 0x7f
#define SCB_FILT_INC_SHIFT 16
#define SCB_INC_MASK 0x7f
#define SCB_INC_SHIFT 8
/* SCB_INT_*_REG bits */
#define INT_BUS_INACTIVE BIT(0)
#define INT_UNEXPECTED_START BIT(1)
#define INT_SCLK_LOW_TIMEOUT BIT(2)
#define INT_SDAT_LOW_TIMEOUT BIT(3)
#define INT_WRITE_ACK_ERR BIT(4)
#define INT_ADDR_ACK_ERR BIT(5)
#define INT_FIFO_FULL BIT(9)
#define INT_FIFO_FILLING BIT(10)
#define INT_FIFO_EMPTY BIT(11)
#define INT_FIFO_EMPTYING BIT(12)
#define INT_TRANSACTION_DONE BIT(15)
#define INT_SLAVE_EVENT BIT(16)
#define INT_TIMING BIT(18)
#define INT_FIFO_FULL_FILLING (INT_FIFO_FULL | INT_FIFO_FILLING)
#define INT_FIFO_EMPTY_EMPTYING (INT_FIFO_EMPTY | INT_FIFO_EMPTYING)
/* Level interrupts need clearing after handling instead of before */
#define INT_LEVEL 0x01e00
/* Don't allow any interrupts while the clock may be off */
#define INT_ENABLE_MASK_INACTIVE 0x00000
/* Interrupt masks for the different driver modes */
#define INT_ENABLE_MASK_RAW INT_TIMING
#define INT_ENABLE_MASK_ATOMIC (INT_TRANSACTION_DONE | \
INT_SLAVE_EVENT | \
INT_ADDR_ACK_ERR | \
INT_WRITE_ACK_ERR)
#define INT_ENABLE_MASK_AUTOMATIC (INT_SCLK_LOW_TIMEOUT | \
INT_ADDR_ACK_ERR | \
INT_WRITE_ACK_ERR | \
INT_FIFO_FULL | \
INT_FIFO_FILLING | \
INT_FIFO_EMPTY | \
INT_FIFO_EMPTYING)
#define INT_ENABLE_MASK_WAITSTOP (INT_SLAVE_EVENT | \
INT_ADDR_ACK_ERR | \
INT_WRITE_ACK_ERR)
/* SCB_STATUS_REG fields */
#define LINESTAT_SCLK_LINE_STATUS BIT(0)
#define LINESTAT_SCLK_EN BIT(1)
#define LINESTAT_SDAT_LINE_STATUS BIT(2)
#define LINESTAT_SDAT_EN BIT(3)
#define LINESTAT_DET_START_STATUS BIT(4)
#define LINESTAT_DET_STOP_STATUS BIT(5)
#define LINESTAT_DET_ACK_STATUS BIT(6)
#define LINESTAT_DET_NACK_STATUS BIT(7)
#define LINESTAT_BUS_IDLE BIT(8)
#define LINESTAT_T_DONE_STATUS BIT(9)
#define LINESTAT_SCLK_OUT_STATUS BIT(10)
#define LINESTAT_SDAT_OUT_STATUS BIT(11)
#define LINESTAT_GEN_LINE_MASK_STATUS BIT(12)
#define LINESTAT_START_BIT_DET BIT(13)
#define LINESTAT_STOP_BIT_DET BIT(14)
#define LINESTAT_ACK_DET BIT(15)
#define LINESTAT_NACK_DET BIT(16)
#define LINESTAT_INPUT_HELD_V BIT(17)
#define LINESTAT_ABORT_DET BIT(18)
#define LINESTAT_ACK_OR_NACK_DET (LINESTAT_ACK_DET | LINESTAT_NACK_DET)
#define LINESTAT_INPUT_DATA 0xff000000
#define LINESTAT_INPUT_DATA_SHIFT 24
#define LINESTAT_CLEAR_SHIFT 13
#define LINESTAT_LATCHED (0x3f << LINESTAT_CLEAR_SHIFT)
/* SCB_OVERRIDE_REG fields */
#define OVERRIDE_SCLK_OVR BIT(0)
#define OVERRIDE_SCLKEN_OVR BIT(1)
#define OVERRIDE_SDAT_OVR BIT(2)
#define OVERRIDE_SDATEN_OVR BIT(3)
#define OVERRIDE_MASTER BIT(9)
#define OVERRIDE_LINE_OVR_EN BIT(10)
#define OVERRIDE_DIRECT BIT(11)
#define OVERRIDE_CMD_SHIFT 4
#define OVERRIDE_CMD_MASK 0x1f
#define OVERRIDE_DATA_SHIFT 24
#define OVERRIDE_SCLK_DOWN (OVERRIDE_LINE_OVR_EN | \
OVERRIDE_SCLKEN_OVR)
#define OVERRIDE_SCLK_UP (OVERRIDE_LINE_OVR_EN | \
OVERRIDE_SCLKEN_OVR | \
OVERRIDE_SCLK_OVR)
#define OVERRIDE_SDAT_DOWN (OVERRIDE_LINE_OVR_EN | \
OVERRIDE_SDATEN_OVR)
#define OVERRIDE_SDAT_UP (OVERRIDE_LINE_OVR_EN | \
OVERRIDE_SDATEN_OVR | \
OVERRIDE_SDAT_OVR)
/* OVERRIDE_CMD values */
#define CMD_PAUSE 0x00
#define CMD_GEN_DATA 0x01
#define CMD_GEN_START 0x02
#define CMD_GEN_STOP 0x03
#define CMD_GEN_ACK 0x04
#define CMD_GEN_NACK 0x05
#define CMD_RET_DATA 0x08
#define CMD_RET_ACK 0x09
/* Fixed timing values */
#define TIMEOUT_TBI 0x0
#define TIMEOUT_TSL 0xffff
#define TIMEOUT_TDL 0x0
/* Transaction timeout */
#define IMG_I2C_TIMEOUT (msecs_to_jiffies(1000))
/*
* Worst incs are 1 (innacurate) and 16*256 (irregular).
* So a sensible inc is the logarithmic mean: 64 (2^6), which is
* in the middle of the valid range (0-127).
*/
#define SCB_OPT_INC 64
/* Setup the clock enable filtering for 25 ns */
#define SCB_FILT_GLITCH 25
/*
* Bits to return from interrupt handler functions for different modes.
* This delays completion until we've finished with the registers, so that the
* function waiting for completion can safely disable the clock to save power.
*/
#define ISR_COMPLETE_M BIT(31)
#define ISR_FATAL_M BIT(30)
#define ISR_WAITSTOP BIT(29)
#define ISR_STATUS_M 0x0000ffff /* contains +ve errno */
#define ISR_COMPLETE(err) (ISR_COMPLETE_M | (ISR_STATUS_M & (err)))
#define ISR_FATAL(err) (ISR_COMPLETE(err) | ISR_FATAL_M)
enum img_i2c_mode {
MODE_INACTIVE,
MODE_RAW,
MODE_ATOMIC,
MODE_AUTOMATIC,
MODE_SEQUENCE,
MODE_FATAL,
MODE_WAITSTOP,
MODE_SUSPEND,
};
/* Timing parameters for i2c modes (in ns) */
struct img_i2c_timings {
const char *name;
unsigned int max_bitrate;
unsigned int tckh, tckl, tsdh, tsdl;
unsigned int tp2s, tpl, tph;
};
/* The timings array must be ordered from slower to faster */
static struct img_i2c_timings timings[] = {
/* Standard mode */
{
.name = "standard",
.max_bitrate = 100000,
.tckh = 4000,
.tckl = 4700,
.tsdh = 4700,
.tsdl = 8700,
.tp2s = 4700,
.tpl = 4700,
.tph = 4000,
},
/* Fast mode */
{
.name = "fast",
.max_bitrate = 400000,
.tckh = 600,
.tckl = 1300,
.tsdh = 600,
.tsdl = 1200,
.tp2s = 1300,
.tpl = 600,
.tph = 600,
},
};
/* Reset dance */
static u8 img_i2c_reset_seq[] = { CMD_GEN_START,
CMD_GEN_DATA, 0xff,
CMD_RET_ACK,
CMD_GEN_START,
CMD_GEN_STOP,
0 };
/* Just issue a stop (after an abort condition) */
static u8 img_i2c_stop_seq[] = { CMD_GEN_STOP,
0 };
/* We're interested in different interrupts depending on the mode */
static unsigned int img_i2c_int_enable_by_mode[] = {
[MODE_INACTIVE] = INT_ENABLE_MASK_INACTIVE,
[MODE_RAW] = INT_ENABLE_MASK_RAW,
[MODE_ATOMIC] = INT_ENABLE_MASK_ATOMIC,
[MODE_AUTOMATIC] = INT_ENABLE_MASK_AUTOMATIC,
[MODE_SEQUENCE] = INT_ENABLE_MASK_ATOMIC,
[MODE_FATAL] = 0,
[MODE_WAITSTOP] = INT_ENABLE_MASK_WAITSTOP,
[MODE_SUSPEND] = 0,
};
/* Atomic command names */
static const char * const img_i2c_atomic_cmd_names[] = {
[CMD_PAUSE] = "PAUSE",
[CMD_GEN_DATA] = "GEN_DATA",
[CMD_GEN_START] = "GEN_START",
[CMD_GEN_STOP] = "GEN_STOP",
[CMD_GEN_ACK] = "GEN_ACK",
[CMD_GEN_NACK] = "GEN_NACK",
[CMD_RET_DATA] = "RET_DATA",
[CMD_RET_ACK] = "RET_ACK",
};
struct img_i2c {
struct i2c_adapter adap;
void __iomem *base;
/*
* The scb core clock is used to get the input frequency, and to disable
* it after every set of transactions to save some power.
*/
struct clk *scb_clk, *sys_clk;
unsigned int bitrate;
bool need_wr_rd_fence;
/* state */
struct completion msg_complete;
spinlock_t lock; /* lock before doing anything with the state */
struct i2c_msg msg;
/* After the last transaction, wait for a stop bit */
bool last_msg;
int msg_status;
enum img_i2c_mode mode;
u32 int_enable; /* depends on mode */
u32 line_status; /* line status over command */
/*
* To avoid slave event interrupts in automatic mode, use a timer to
* poll the abort condition if we don't get an interrupt for too long.
*/
struct timer_list check_timer;
bool t_halt;
/* atomic mode state */
bool at_t_done;
bool at_slave_event;
int at_cur_cmd;
u8 at_cur_data;
/* Sequence: either reset or stop. See img_i2c_sequence. */
u8 *seq;
/* raw mode */
unsigned int raw_timeout;
};
static void img_i2c_writel(struct img_i2c *i2c, u32 offset, u32 value)
{
writel(value, i2c->base + offset);
}
static u32 img_i2c_readl(struct img_i2c *i2c, u32 offset)
{
return readl(i2c->base + offset);
}
/*
* The code to read from the master read fifo, and write to the master
* write fifo, checks a bit in an SCB register before every byte to
* ensure that the fifo is not full (write fifo) or empty (read fifo).
* Due to clock domain crossing inside the SCB block the updated value
* of this bit is only visible after 2 cycles.
*
* The scb_wr_rd_fence() function does 2 dummy writes (to the read-only
* revision register), and it's called after reading from or writing to the
* fifos to ensure that subsequent reads of the fifo status bits do not read
* stale values.
*/
static void img_i2c_wr_rd_fence(struct img_i2c *i2c)
{
if (i2c->need_wr_rd_fence) {
img_i2c_writel(i2c, SCB_CORE_REV_REG, 0);
img_i2c_writel(i2c, SCB_CORE_REV_REG, 0);
}
}
static void img_i2c_switch_mode(struct img_i2c *i2c, enum img_i2c_mode mode)
{
i2c->mode = mode;
i2c->int_enable = img_i2c_int_enable_by_mode[mode];
i2c->line_status = 0;
}
static void img_i2c_raw_op(struct img_i2c *i2c)
{
i2c->raw_timeout = 0;
img_i2c_writel(i2c, SCB_OVERRIDE_REG,
OVERRIDE_SCLKEN_OVR |
OVERRIDE_SDATEN_OVR |
OVERRIDE_MASTER |
OVERRIDE_LINE_OVR_EN |
OVERRIDE_DIRECT |
((i2c->at_cur_cmd & OVERRIDE_CMD_MASK) << OVERRIDE_CMD_SHIFT) |
(i2c->at_cur_data << OVERRIDE_DATA_SHIFT));
}
static const char *img_i2c_atomic_op_name(unsigned int cmd)
{
if (unlikely(cmd >= ARRAY_SIZE(img_i2c_atomic_cmd_names)))
return "UNKNOWN";
return img_i2c_atomic_cmd_names[cmd];
}
/* Send a single atomic mode command to the hardware */
static void img_i2c_atomic_op(struct img_i2c *i2c, int cmd, u8 data)
{
i2c->at_cur_cmd = cmd;
i2c->at_cur_data = data;
/* work around lack of data setup time when generating data */
if (cmd == CMD_GEN_DATA && i2c->mode == MODE_ATOMIC) {
u32 line_status = img_i2c_readl(i2c, SCB_STATUS_REG);
if (line_status & LINESTAT_SDAT_LINE_STATUS && !(data & 0x80)) {
/* hold the data line down for a moment */
img_i2c_switch_mode(i2c, MODE_RAW);
img_i2c_raw_op(i2c);
return;
}
}
dev_dbg(i2c->adap.dev.parent,
"atomic cmd=%s (%d) data=%#x\n",
img_i2c_atomic_op_name(cmd), cmd, data);
i2c->at_t_done = (cmd == CMD_RET_DATA || cmd == CMD_RET_ACK);
i2c->at_slave_event = false;
i2c->line_status = 0;
img_i2c_writel(i2c, SCB_OVERRIDE_REG,
((cmd & OVERRIDE_CMD_MASK) << OVERRIDE_CMD_SHIFT) |
OVERRIDE_MASTER |
OVERRIDE_DIRECT |
(data << OVERRIDE_DATA_SHIFT));
}
/* Start a transaction in atomic mode */
static void img_i2c_atomic_start(struct img_i2c *i2c)
{
img_i2c_switch_mode(i2c, MODE_ATOMIC);
img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
img_i2c_atomic_op(i2c, CMD_GEN_START, 0x00);
}
static void img_i2c_soft_reset(struct img_i2c *i2c)
{
i2c->t_halt = false;
img_i2c_writel(i2c, SCB_CONTROL_REG, 0);
img_i2c_writel(i2c, SCB_CONTROL_REG,
SCB_CONTROL_CLK_ENABLE | SCB_CONTROL_SOFT_RESET);
}
/* enable or release transaction halt for control of repeated starts */
static void img_i2c_transaction_halt(struct img_i2c *i2c, bool t_halt)
{
u32 val;
if (i2c->t_halt == t_halt)
return;
i2c->t_halt = t_halt;
val = img_i2c_readl(i2c, SCB_CONTROL_REG);
if (t_halt)
val |= SCB_CONTROL_TRANSACTION_HALT;
else
val &= ~SCB_CONTROL_TRANSACTION_HALT;
img_i2c_writel(i2c, SCB_CONTROL_REG, val);
}
/* Drain data from the FIFO into the buffer (automatic mode) */
static void img_i2c_read_fifo(struct img_i2c *i2c)
{
while (i2c->msg.len) {
u32 fifo_status;
u8 data;
img_i2c_wr_rd_fence(i2c);
fifo_status = img_i2c_readl(i2c, SCB_FIFO_STATUS_REG);
if (fifo_status & FIFO_READ_EMPTY)
break;
data = img_i2c_readl(i2c, SCB_READ_DATA_REG);
*i2c->msg.buf = data;
img_i2c_writel(i2c, SCB_READ_FIFO_REG, 0xff);
i2c->msg.len--;
i2c->msg.buf++;
}
}
/* Fill the FIFO with data from the buffer (automatic mode) */
static void img_i2c_write_fifo(struct img_i2c *i2c)
{
while (i2c->msg.len) {
u32 fifo_status;
img_i2c_wr_rd_fence(i2c);
fifo_status = img_i2c_readl(i2c, SCB_FIFO_STATUS_REG);
if (fifo_status & FIFO_WRITE_FULL)
break;
img_i2c_writel(i2c, SCB_WRITE_DATA_REG, *i2c->msg.buf);
i2c->msg.len--;
i2c->msg.buf++;
}
/* Disable fifo emptying interrupt if nothing more to write */
if (!i2c->msg.len)
i2c->int_enable &= ~INT_FIFO_EMPTYING;
}
/* Start a read transaction in automatic mode */
static void img_i2c_read(struct img_i2c *i2c)
{
img_i2c_switch_mode(i2c, MODE_AUTOMATIC);
if (!i2c->last_msg)
i2c->int_enable |= INT_SLAVE_EVENT;
img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
img_i2c_writel(i2c, SCB_READ_ADDR_REG, i2c->msg.addr);
img_i2c_writel(i2c, SCB_READ_COUNT_REG, i2c->msg.len);
img_i2c_transaction_halt(i2c, false);
mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
}
/* Start a write transaction in automatic mode */
static void img_i2c_write(struct img_i2c *i2c)
{
img_i2c_switch_mode(i2c, MODE_AUTOMATIC);
if (!i2c->last_msg)
i2c->int_enable |= INT_SLAVE_EVENT;
img_i2c_writel(i2c, SCB_WRITE_ADDR_REG, i2c->msg.addr);
img_i2c_writel(i2c, SCB_WRITE_COUNT_REG, i2c->msg.len);
img_i2c_transaction_halt(i2c, false);
mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
img_i2c_write_fifo(i2c);
/* img_i2c_write_fifo() may modify int_enable */
img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
}
/*
* Indicate that the transaction is complete. This is called from the
* ISR to wake up the waiting thread, after which the ISR must not
* access any more SCB registers.
*/
static void img_i2c_complete_transaction(struct img_i2c *i2c, int status)
{
img_i2c_switch_mode(i2c, MODE_INACTIVE);
if (status) {
i2c->msg_status = status;
img_i2c_transaction_halt(i2c, false);
}
complete(&i2c->msg_complete);
}
static unsigned int img_i2c_raw_atomic_delay_handler(struct img_i2c *i2c,
u32 int_status, u32 line_status)
{
/* Stay in raw mode for this, so we don't just loop infinitely */
img_i2c_atomic_op(i2c, i2c->at_cur_cmd, i2c->at_cur_data);
img_i2c_switch_mode(i2c, MODE_ATOMIC);
return 0;
}
static unsigned int img_i2c_raw(struct img_i2c *i2c, u32 int_status,
u32 line_status)
{
if (int_status & INT_TIMING) {
if (i2c->raw_timeout == 0)
return img_i2c_raw_atomic_delay_handler(i2c,
int_status, line_status);
--i2c->raw_timeout;
}
return 0;
}
static unsigned int img_i2c_sequence(struct img_i2c *i2c, u32 int_status)
{
static const unsigned int continue_bits[] = {
[CMD_GEN_START] = LINESTAT_START_BIT_DET,
[CMD_GEN_DATA] = LINESTAT_INPUT_HELD_V,
[CMD_RET_ACK] = LINESTAT_ACK_DET | LINESTAT_NACK_DET,
[CMD_RET_DATA] = LINESTAT_INPUT_HELD_V,
[CMD_GEN_STOP] = LINESTAT_STOP_BIT_DET,
};
int next_cmd = -1;
u8 next_data = 0x00;
if (int_status & INT_SLAVE_EVENT)
i2c->at_slave_event = true;
if (int_status & INT_TRANSACTION_DONE)
i2c->at_t_done = true;
if (!i2c->at_slave_event || !i2c->at_t_done)
return 0;
/* wait if no continue bits are set */
if (i2c->at_cur_cmd >= 0 &&
i2c->at_cur_cmd < ARRAY_SIZE(continue_bits)) {
unsigned int cont_bits = continue_bits[i2c->at_cur_cmd];
if (cont_bits) {
cont_bits |= LINESTAT_ABORT_DET;
if (!(i2c->line_status & cont_bits))
return 0;
}
}
/* follow the sequence of commands in i2c->seq */
next_cmd = *i2c->seq;
/* stop on a nil */
if (!next_cmd) {
img_i2c_writel(i2c, SCB_OVERRIDE_REG, 0);
return ISR_COMPLETE(0);
}
/* when generating data, the next byte is the data */
if (next_cmd == CMD_GEN_DATA) {
++i2c->seq;
next_data = *i2c->seq;
}
++i2c->seq;
img_i2c_atomic_op(i2c, next_cmd, next_data);
return 0;
}
static void img_i2c_reset_start(struct img_i2c *i2c)
{
/* Initiate the magic dance */
img_i2c_switch_mode(i2c, MODE_SEQUENCE);
img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
i2c->seq = img_i2c_reset_seq;
i2c->at_slave_event = true;
i2c->at_t_done = true;
i2c->at_cur_cmd = -1;
/* img_i2c_reset_seq isn't empty so the following won't fail */
img_i2c_sequence(i2c, 0);
}
static void img_i2c_stop_start(struct img_i2c *i2c)
{
/* Initiate a stop bit sequence */
img_i2c_switch_mode(i2c, MODE_SEQUENCE);
img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
i2c->seq = img_i2c_stop_seq;
i2c->at_slave_event = true;
i2c->at_t_done = true;
i2c->at_cur_cmd = -1;
/* img_i2c_stop_seq isn't empty so the following won't fail */
img_i2c_sequence(i2c, 0);
}
static unsigned int img_i2c_atomic(struct img_i2c *i2c,
u32 int_status,
u32 line_status)
{
int next_cmd = -1;
u8 next_data = 0x00;
if (int_status & INT_SLAVE_EVENT)
i2c->at_slave_event = true;
if (int_status & INT_TRANSACTION_DONE)
i2c->at_t_done = true;
if (!i2c->at_slave_event || !i2c->at_t_done)
goto next_atomic_cmd;
if (i2c->line_status & LINESTAT_ABORT_DET) {
dev_dbg(i2c->adap.dev.parent, "abort condition detected\n");
next_cmd = CMD_GEN_STOP;
i2c->msg_status = -EIO;
goto next_atomic_cmd;
}
/* i2c->at_cur_cmd may have completed */
switch (i2c->at_cur_cmd) {
case CMD_GEN_START:
next_cmd = CMD_GEN_DATA;
next_data = (i2c->msg.addr << 1);
if (i2c->msg.flags & I2C_M_RD)
next_data |= 0x1;
break;
case CMD_GEN_DATA:
if (i2c->line_status & LINESTAT_INPUT_HELD_V)
next_cmd = CMD_RET_ACK;
break;
case CMD_RET_ACK:
if (i2c->line_status & LINESTAT_ACK_DET) {
if (i2c->msg.len == 0) {
next_cmd = CMD_GEN_STOP;
} else if (i2c->msg.flags & I2C_M_RD) {
next_cmd = CMD_RET_DATA;
} else {
next_cmd = CMD_GEN_DATA;
next_data = *i2c->msg.buf;
--i2c->msg.len;
++i2c->msg.buf;
}
} else if (i2c->line_status & LINESTAT_NACK_DET) {
i2c->msg_status = -EIO;
next_cmd = CMD_GEN_STOP;
}
break;
case CMD_RET_DATA:
if (i2c->line_status & LINESTAT_INPUT_HELD_V) {
*i2c->msg.buf = (i2c->line_status &
LINESTAT_INPUT_DATA)
>> LINESTAT_INPUT_DATA_SHIFT;
--i2c->msg.len;
++i2c->msg.buf;
if (i2c->msg.len)
next_cmd = CMD_GEN_ACK;
else
next_cmd = CMD_GEN_NACK;
}
break;
case CMD_GEN_ACK:
if (i2c->line_status & LINESTAT_ACK_DET) {
next_cmd = CMD_RET_DATA;
} else {
i2c->msg_status = -EIO;
next_cmd = CMD_GEN_STOP;
}
break;
case CMD_GEN_NACK:
next_cmd = CMD_GEN_STOP;
break;
case CMD_GEN_STOP:
img_i2c_writel(i2c, SCB_OVERRIDE_REG, 0);
return ISR_COMPLETE(0);
default:
dev_err(i2c->adap.dev.parent, "bad atomic command %d\n",
i2c->at_cur_cmd);
i2c->msg_status = -EIO;
next_cmd = CMD_GEN_STOP;
break;
}
next_atomic_cmd:
if (next_cmd != -1) {
/* don't actually stop unless we're the last transaction */
if (next_cmd == CMD_GEN_STOP && !i2c->msg_status &&
!i2c->last_msg)
return ISR_COMPLETE(0);
img_i2c_atomic_op(i2c, next_cmd, next_data);
}
return 0;
}
/*
* Timer function to check if something has gone wrong in automatic mode (so we
* don't have to handle so many interrupts just to catch an exception).
*/
static void img_i2c_check_timer(unsigned long arg)
{
struct img_i2c *i2c = (struct img_i2c *)arg;
unsigned long flags;
unsigned int line_status;
spin_lock_irqsave(&i2c->lock, flags);
line_status = img_i2c_readl(i2c, SCB_STATUS_REG);
/* check for an abort condition */
if (line_status & LINESTAT_ABORT_DET) {
dev_dbg(i2c->adap.dev.parent,
"abort condition detected by check timer\n");
/* enable slave event interrupt mask to trigger irq */
img_i2c_writel(i2c, SCB_INT_MASK_REG,
i2c->int_enable | INT_SLAVE_EVENT);
}
spin_unlock_irqrestore(&i2c->lock, flags);
}
static unsigned int img_i2c_auto(struct img_i2c *i2c,
unsigned int int_status,
unsigned int line_status)
{
if (int_status & (INT_WRITE_ACK_ERR | INT_ADDR_ACK_ERR))
return ISR_COMPLETE(EIO);
if (line_status & LINESTAT_ABORT_DET) {
dev_dbg(i2c->adap.dev.parent, "abort condition detected\n");
/* empty the read fifo */
if ((i2c->msg.flags & I2C_M_RD) &&
(int_status & INT_FIFO_FULL_FILLING))
img_i2c_read_fifo(i2c);
/* use atomic mode and try to force a stop bit */
i2c->msg_status = -EIO;
img_i2c_stop_start(i2c);
return 0;
}
/* Enable transaction halt on start bit */
if (!i2c->last_msg && i2c->line_status & LINESTAT_START_BIT_DET) {
img_i2c_transaction_halt(i2c, true);
/* we're no longer interested in the slave event */
i2c->int_enable &= ~INT_SLAVE_EVENT;
}
mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
if (i2c->msg.flags & I2C_M_RD) {
if (int_status & INT_FIFO_FULL_FILLING) {
img_i2c_read_fifo(i2c);
if (i2c->msg.len == 0)
return ISR_WAITSTOP;
}
} else {
if (int_status & INT_FIFO_EMPTY_EMPTYING) {
/*
* The write fifo empty indicates that we're in the
* last byte so it's safe to start a new write
* transaction without losing any bytes from the
* previous one.
* see 2.3.7 Repeated Start Transactions.
*/
if ((int_status & INT_FIFO_EMPTY) &&
i2c->msg.len == 0)
return ISR_WAITSTOP;
img_i2c_write_fifo(i2c);
}
}
return 0;
}
static irqreturn_t img_i2c_isr(int irq, void *dev_id)
{
struct img_i2c *i2c = (struct img_i2c *)dev_id;
u32 int_status, line_status;
/* We handle transaction completion AFTER accessing registers */
unsigned int hret;
/* Read interrupt status register. */
int_status = img_i2c_readl(i2c, SCB_INT_STATUS_REG);
/* Clear detected interrupts. */
img_i2c_writel(i2c, SCB_INT_CLEAR_REG, int_status);
/*
* Read line status and clear it until it actually is clear. We have
* to be careful not to lose any line status bits that get latched.
*/
line_status = img_i2c_readl(i2c, SCB_STATUS_REG);
if (line_status & LINESTAT_LATCHED) {
img_i2c_writel(i2c, SCB_CLEAR_REG,
(line_status & LINESTAT_LATCHED)
>> LINESTAT_CLEAR_SHIFT);
img_i2c_wr_rd_fence(i2c);
}
spin_lock(&i2c->lock);
/* Keep track of line status bits received */
i2c->line_status &= ~LINESTAT_INPUT_DATA;
i2c->line_status |= line_status;
/*
* Certain interrupts indicate that sclk low timeout is not
* a problem. If any of these are set, just continue.
*/
if ((int_status & INT_SCLK_LOW_TIMEOUT) &&
!(int_status & (INT_SLAVE_EVENT |
INT_FIFO_EMPTY |
INT_FIFO_FULL))) {
dev_crit(i2c->adap.dev.parent,
"fatal: clock low timeout occurred %s addr 0x%02x\n",
(i2c->msg.flags & I2C_M_RD) ? "reading" : "writing",
i2c->msg.addr);
hret = ISR_FATAL(EIO);
goto out;
}
if (i2c->mode == MODE_ATOMIC)
hret = img_i2c_atomic(i2c, int_status, line_status);
else if (i2c->mode == MODE_AUTOMATIC)
hret = img_i2c_auto(i2c, int_status, line_status);
else if (i2c->mode == MODE_SEQUENCE)
hret = img_i2c_sequence(i2c, int_status);
else if (i2c->mode == MODE_WAITSTOP && (int_status & INT_SLAVE_EVENT) &&
(line_status & LINESTAT_STOP_BIT_DET))
hret = ISR_COMPLETE(0);
else if (i2c->mode == MODE_RAW)
hret = img_i2c_raw(i2c, int_status, line_status);
else
hret = 0;
/* Clear detected level interrupts. */
img_i2c_writel(i2c, SCB_INT_CLEAR_REG, int_status & INT_LEVEL);
out:
if (hret & ISR_WAITSTOP) {
/*
* Only wait for stop on last message.
* Also we may already have detected the stop bit.
*/
if (!i2c->last_msg || i2c->line_status & LINESTAT_STOP_BIT_DET)
hret = ISR_COMPLETE(0);
else
img_i2c_switch_mode(i2c, MODE_WAITSTOP);
}
/* now we've finished using regs, handle transaction completion */
if (hret & ISR_COMPLETE_M) {
int status = -(hret & ISR_STATUS_M);
img_i2c_complete_transaction(i2c, status);
if (hret & ISR_FATAL_M)
img_i2c_switch_mode(i2c, MODE_FATAL);
}
/* Enable interrupts (int_enable may be altered by changing mode) */
img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
spin_unlock(&i2c->lock);
return IRQ_HANDLED;
}
/* Force a bus reset sequence and wait for it to complete */
static int img_i2c_reset_bus(struct img_i2c *i2c)
{
unsigned long flags;
unsigned long time_left;
spin_lock_irqsave(&i2c->lock, flags);
reinit_completion(&i2c->msg_complete);
img_i2c_reset_start(i2c);
spin_unlock_irqrestore(&i2c->lock, flags);
time_left = wait_for_completion_timeout(&i2c->msg_complete,
IMG_I2C_TIMEOUT);
if (time_left == 0)
return -ETIMEDOUT;
return 0;
}
static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
struct img_i2c *i2c = i2c_get_adapdata(adap);
bool atomic = false;
int i, ret;
unsigned long time_left;
if (i2c->mode == MODE_SUSPEND) {
WARN(1, "refusing to service transaction in suspended state\n");
return -EIO;
}
if (i2c->mode == MODE_FATAL)
return -EIO;
for (i = 0; i < num; i++) {
if (likely(msgs[i].len))
continue;
/*
* 0 byte reads are not possible because the slave could try
* and pull the data line low, preventing a stop bit.
*/
if (unlikely(msgs[i].flags & I2C_M_RD))
return -EIO;
/*
* 0 byte writes are possible and used for probing, but we
* cannot do them in automatic mode, so use atomic mode
* instead.
*/
atomic = true;
}
ret = clk_prepare_enable(i2c->scb_clk);
if (ret)
return ret;
for (i = 0; i < num; i++) {
struct i2c_msg *msg = &msgs[i];
unsigned long flags;
spin_lock_irqsave(&i2c->lock, flags);
/*
* Make a copy of the message struct. We mustn't modify the
* original or we'll confuse drivers and i2c-dev.
*/
i2c->msg = *msg;
i2c->msg_status = 0;
/*
* After the last message we must have waited for a stop bit.
* Not waiting can cause problems when the clock is disabled
* before the stop bit is sent, and the linux I2C interface
* requires separate transfers not to joined with repeated
* start.
*/
i2c->last_msg = (i == num - 1);
reinit_completion(&i2c->msg_complete);
if (atomic)
img_i2c_atomic_start(i2c);
else if (msg->flags & I2C_M_RD)
img_i2c_read(i2c);
else
img_i2c_write(i2c);
spin_unlock_irqrestore(&i2c->lock, flags);
time_left = wait_for_completion_timeout(&i2c->msg_complete,
IMG_I2C_TIMEOUT);
del_timer_sync(&i2c->check_timer);
if (time_left == 0) {
dev_err(adap->dev.parent, "i2c transfer timed out\n");
i2c->msg_status = -ETIMEDOUT;
break;
}
if (i2c->msg_status)
break;
}
clk_disable_unprepare(i2c->scb_clk);
return i2c->msg_status ? i2c->msg_status : num;
}
static u32 img_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm img_i2c_algo = {
.master_xfer = img_i2c_xfer,
.functionality = img_i2c_func,
};
static int img_i2c_init(struct img_i2c *i2c)
{
unsigned int clk_khz, bitrate_khz, clk_period, tckh, tckl, tsdh;
unsigned int i, ret, data, prescale, inc, int_bitrate, filt;
struct img_i2c_timings timing;
u32 rev;
ret = clk_prepare_enable(i2c->scb_clk);
if (ret)
return ret;
rev = img_i2c_readl(i2c, SCB_CORE_REV_REG);
if ((rev & 0x00ffffff) < 0x00020200) {
dev_info(i2c->adap.dev.parent,
"Unknown hardware revision (%d.%d.%d.%d)\n",
(rev >> 24) & 0xff, (rev >> 16) & 0xff,
(rev >> 8) & 0xff, rev & 0xff);
clk_disable_unprepare(i2c->scb_clk);
return -EINVAL;
}
/* Fencing enabled by default. */
i2c->need_wr_rd_fence = true;
bitrate_khz = i2c->bitrate / 1000;
clk_khz = clk_get_rate(i2c->scb_clk) / 1000;
/* Determine what mode we're in from the bitrate */
timing = timings[0];
for (i = 0; i < ARRAY_SIZE(timings); i++) {
if (i2c->bitrate <= timings[i].max_bitrate) {
timing = timings[i];
break;
}
}
/* Find the prescale that would give us that inc (approx delay = 0) */
prescale = SCB_OPT_INC * clk_khz / (256 * 16 * bitrate_khz);
prescale = clamp_t(unsigned int, prescale, 1, 8);
clk_khz /= prescale;
/* Setup the clock increment value */
inc = (256 * 16 * bitrate_khz) / clk_khz;
/*
* The clock generation logic allows to filter glitches on the bus.
* This filter is able to remove bus glitches shorter than 50ns.
* If the clock enable rate is greater than 20 MHz, no filtering
* is required, so we need to disable it.
* If it's between the 20-40 MHz range, there's no need to divide
* the clock to get a filter.
*/
if (clk_khz < 20000) {
filt = SCB_FILT_DISABLE;
} else if (clk_khz < 40000) {
filt = SCB_FILT_BYPASS;
} else {
/* Calculate filter clock */
filt = (64000 / ((clk_khz / 1000) * SCB_FILT_GLITCH));
/* Scale up if needed */
if (64000 % ((clk_khz / 1000) * SCB_FILT_GLITCH))
inc++;
if (filt > SCB_FILT_INC_MASK)
filt = SCB_FILT_INC_MASK;
filt = (filt & SCB_FILT_INC_MASK) << SCB_FILT_INC_SHIFT;
}
data = filt | ((inc & SCB_INC_MASK) << SCB_INC_SHIFT) | (prescale - 1);
img_i2c_writel(i2c, SCB_CLK_SET_REG, data);
/* Obtain the clock period of the fx16 clock in ns */
clk_period = (256 * 1000000) / (clk_khz * inc);
/* Calculate the bitrate in terms of internal clock pulses */
int_bitrate = 1000000 / (bitrate_khz * clk_period);
if ((1000000 % (bitrate_khz * clk_period)) >=
((bitrate_khz * clk_period) / 2))
int_bitrate++;
/* Setup TCKH value */
tckh = timing.tckh / clk_period;
if (timing.tckh % clk_period)
tckh++;
if (tckh > 0)
data = tckh - 1;
else
data = 0;
img_i2c_writel(i2c, SCB_TIME_TCKH_REG, data);
/* Setup TCKL value */
tckl = int_bitrate - tckh;
if (tckl > 0)
data = tckl - 1;
else
data = 0;
img_i2c_writel(i2c, SCB_TIME_TCKL_REG, data);
/* Setup TSDH value */
tsdh = timing.tsdh / clk_period;
if (timing.tsdh % clk_period)
tsdh++;
if (tsdh > 1)
data = tsdh - 1;
else
data = 0x01;
img_i2c_writel(i2c, SCB_TIME_TSDH_REG, data);
/* This value is used later */
tsdh = data;
/* Setup TPL value */
data = timing.tpl / clk_period;
if (data > 0)
--data;
img_i2c_writel(i2c, SCB_TIME_TPL_REG, data);
/* Setup TPH value */
data = timing.tph / clk_period;
if (data > 0)
--data;
img_i2c_writel(i2c, SCB_TIME_TPH_REG, data);
/* Setup TSDL value to TPL + TSDH + 2 */
img_i2c_writel(i2c, SCB_TIME_TSDL_REG, data + tsdh + 2);
/* Setup TP2S value */
data = timing.tp2s / clk_period;
if (data > 0)
--data;
img_i2c_writel(i2c, SCB_TIME_TP2S_REG, data);
img_i2c_writel(i2c, SCB_TIME_TBI_REG, TIMEOUT_TBI);
img_i2c_writel(i2c, SCB_TIME_TSL_REG, TIMEOUT_TSL);
img_i2c_writel(i2c, SCB_TIME_TDL_REG, TIMEOUT_TDL);
/* Take module out of soft reset and enable clocks */
img_i2c_soft_reset(i2c);
/* Disable all interrupts */
img_i2c_writel(i2c, SCB_INT_MASK_REG, 0);
/* Clear all interrupts */
img_i2c_writel(i2c, SCB_INT_CLEAR_REG, ~0);
/* Clear the scb_line_status events */
img_i2c_writel(i2c, SCB_CLEAR_REG, ~0);
/* Enable interrupts */
img_i2c_writel(i2c, SCB_INT_MASK_REG, i2c->int_enable);
/* Perform a synchronous sequence to reset the bus */
ret = img_i2c_reset_bus(i2c);
clk_disable_unprepare(i2c->scb_clk);
return ret;
}
static int img_i2c_probe(struct platform_device *pdev)
{
struct device_node *node = pdev->dev.of_node;
struct img_i2c *i2c;
struct resource *res;
int irq, ret;
u32 val;
i2c = devm_kzalloc(&pdev->dev, sizeof(struct img_i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
i2c->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(i2c->base))
return PTR_ERR(i2c->base);
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(&pdev->dev, "can't get irq number\n");
return irq;
}
i2c->sys_clk = devm_clk_get(&pdev->dev, "sys");
if (IS_ERR(i2c->sys_clk)) {
dev_err(&pdev->dev, "can't get system clock\n");
return PTR_ERR(i2c->sys_clk);
}
i2c->scb_clk = devm_clk_get(&pdev->dev, "scb");
if (IS_ERR(i2c->scb_clk)) {
dev_err(&pdev->dev, "can't get core clock\n");
return PTR_ERR(i2c->scb_clk);
}
ret = devm_request_irq(&pdev->dev, irq, img_i2c_isr, 0,
pdev->name, i2c);
if (ret) {
dev_err(&pdev->dev, "can't request irq %d\n", irq);
return ret;
}
/* Set up the exception check timer */
init_timer(&i2c->check_timer);
i2c->check_timer.function = img_i2c_check_timer;
i2c->check_timer.data = (unsigned long)i2c;
i2c->bitrate = timings[0].max_bitrate;
if (!of_property_read_u32(node, "clock-frequency", &val))
i2c->bitrate = val;
i2c_set_adapdata(&i2c->adap, i2c);
i2c->adap.dev.parent = &pdev->dev;
i2c->adap.dev.of_node = node;
i2c->adap.owner = THIS_MODULE;
i2c->adap.algo = &img_i2c_algo;
i2c->adap.retries = 5;
i2c->adap.nr = pdev->id;
snprintf(i2c->adap.name, sizeof(i2c->adap.name), "IMG SCB I2C");
img_i2c_switch_mode(i2c, MODE_INACTIVE);
spin_lock_init(&i2c->lock);
init_completion(&i2c->msg_complete);
platform_set_drvdata(pdev, i2c);
ret = clk_prepare_enable(i2c->sys_clk);
if (ret)
return ret;
ret = img_i2c_init(i2c);
if (ret)
goto disable_clk;
ret = i2c_add_numbered_adapter(&i2c->adap);
if (ret < 0) {
dev_err(&pdev->dev, "failed to add adapter\n");
goto disable_clk;
}
return 0;
disable_clk:
clk_disable_unprepare(i2c->sys_clk);
return ret;
}
static int img_i2c_remove(struct platform_device *dev)
{
struct img_i2c *i2c = platform_get_drvdata(dev);
i2c_del_adapter(&i2c->adap);
clk_disable_unprepare(i2c->sys_clk);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int img_i2c_suspend(struct device *dev)
{
struct img_i2c *i2c = dev_get_drvdata(dev);
img_i2c_switch_mode(i2c, MODE_SUSPEND);
clk_disable_unprepare(i2c->sys_clk);
return 0;
}
static int img_i2c_resume(struct device *dev)
{
struct img_i2c *i2c = dev_get_drvdata(dev);
int ret;
ret = clk_prepare_enable(i2c->sys_clk);
if (ret)
return ret;
img_i2c_init(i2c);
return 0;
}
#endif /* CONFIG_PM_SLEEP */
static SIMPLE_DEV_PM_OPS(img_i2c_pm, img_i2c_suspend, img_i2c_resume);
static const struct of_device_id img_scb_i2c_match[] = {
{ .compatible = "img,scb-i2c" },
{ }
};
MODULE_DEVICE_TABLE(of, img_scb_i2c_match);
static struct platform_driver img_scb_i2c_driver = {
.driver = {
.name = "img-i2c-scb",
.of_match_table = img_scb_i2c_match,
.pm = &img_i2c_pm,
},
.probe = img_i2c_probe,
.remove = img_i2c_remove,
};
module_platform_driver(img_scb_i2c_driver);
MODULE_AUTHOR("James Hogan <james.hogan@imgtec.com>");
MODULE_DESCRIPTION("IMG host I2C driver");
MODULE_LICENSE("GPL v2");
