/*
* Copyright 2014 Google, Inc
* Author: Alexandru M Stan <amstan@chromium.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include "clk.h"
struct rockchip_mmc_clock {
struct clk_hw hw;
void __iomem *reg;
int id;
int shift;
int cached_phase;
struct notifier_block clk_rate_change_nb;
};
#define to_mmc_clock(_hw) container_of(_hw, struct rockchip_mmc_clock, hw)
#define RK3288_MMC_CLKGEN_DIV 2
static unsigned long rockchip_mmc_recalc(struct clk_hw *hw,
unsigned long parent_rate)
{
return parent_rate / RK3288_MMC_CLKGEN_DIV;
}
#define ROCKCHIP_MMC_DELAY_SEL BIT(10)
#define ROCKCHIP_MMC_DEGREE_MASK 0x3
#define ROCKCHIP_MMC_DELAYNUM_OFFSET 2
#define ROCKCHIP_MMC_DELAYNUM_MASK (0xff << ROCKCHIP_MMC_DELAYNUM_OFFSET)
#define PSECS_PER_SEC 1000000000000LL
/*
* Each fine delay is between 44ps-77ps. Assume each fine delay is 60ps to
* simplify calculations. So 45degs could be anywhere between 33deg and 57.8deg.
*/
#define ROCKCHIP_MMC_DELAY_ELEMENT_PSEC 60
static int rockchip_mmc_get_phase(struct clk_hw *hw)
{
struct rockchip_mmc_clock *mmc_clock = to_mmc_clock(hw);
unsigned long rate = clk_hw_get_rate(hw);
u32 raw_value;
u16 degrees;
u32 delay_num = 0;
/* See the comment for rockchip_mmc_set_phase below */
if (!rate)
return -EINVAL;
raw_value = readl(mmc_clock->reg) >> (mmc_clock->shift);
degrees = (raw_value & ROCKCHIP_MMC_DEGREE_MASK) * 90;
if (raw_value & ROCKCHIP_MMC_DELAY_SEL) {
/* degrees/delaynum * 10000 */
unsigned long factor = (ROCKCHIP_MMC_DELAY_ELEMENT_PSEC / 10) *
36 * (rate / 1000000);
delay_num = (raw_value & ROCKCHIP_MMC_DELAYNUM_MASK);
delay_num >>= ROCKCHIP_MMC_DELAYNUM_OFFSET;
degrees += DIV_ROUND_CLOSEST(delay_num * factor, 10000);
}
return degrees % 360;
}
static int rockchip_mmc_set_phase(struct clk_hw *hw, int degrees)
{
struct rockchip_mmc_clock *mmc_clock = to_mmc_clock(hw);
unsigned long rate = clk_hw_get_rate(hw);
u8 nineties, remainder;
u8 delay_num;
u32 raw_value;
u32 delay;
/*
* The below calculation is based on the output clock from
* MMC host to the card, which expects the phase clock inherits
* the clock rate from its parent, namely the output clock
* provider of MMC host. However, things may go wrong if
* (1) It is orphan.
* (2) It is assigned to the wrong parent.
*
* This check help debug the case (1), which seems to be the
* most likely problem we often face and which makes it difficult
* for people to debug unstable mmc tuning results.
*/
if (!rate) {
pr_err("%s: invalid clk rate\n", __func__);
return -EINVAL;
}
nineties = degrees / 90;
remainder = (degrees % 90);
/*
* Due to the inexact nature of the "fine" delay, we might
* actually go non-monotonic. We don't go _too_ monotonic
* though, so we should be OK. Here are options of how we may
* work:
*
* Ideally we end up with:
* 1.0, 2.0, ..., 69.0, 70.0, ..., 89.0, 90.0
*
* On one extreme (if delay is actually 44ps):
* .73, 1.5, ..., 50.6, 51.3, ..., 65.3, 90.0
* The other (if delay is actually 77ps):
* 1.3, 2.6, ..., 88.6. 89.8, ..., 114.0, 90
*
* It's possible we might make a delay that is up to 25
* degrees off from what we think we're making. That's OK
* though because we should be REALLY far from any bad range.
*/
/*
* Convert to delay; do a little extra work to make sure we
* don't overflow 32-bit / 64-bit numbers.
*/
delay = 10000000; /* PSECS_PER_SEC / 10000 / 10 */
delay *= remainder;
delay = DIV_ROUND_CLOSEST(delay,
(rate / 1000) * 36 *
(ROCKCHIP_MMC_DELAY_ELEMENT_PSEC / 10));
delay_num = (u8) min_t(u32, delay, 255);
raw_value = delay_num ? ROCKCHIP_MMC_DELAY_SEL : 0;
raw_value |= delay_num << ROCKCHIP_MMC_DELAYNUM_OFFSET;
raw_value |= nineties;
writel(HIWORD_UPDATE(raw_value, 0x07ff, mmc_clock->shift),
mmc_clock->reg);
pr_debug("%s->set_phase(%d) delay_nums=%u reg[0x%p]=0x%03x actual_degrees=%d\n",
clk_hw_get_name(hw), degrees, delay_num,
mmc_clock->reg, raw_value>>(mmc_clock->shift),
rockchip_mmc_get_phase(hw)
);
return 0;
}
static const struct clk_ops rockchip_mmc_clk_ops = {
.recalc_rate = rockchip_mmc_recalc,
.get_phase = rockchip_mmc_get_phase,
.set_phase = rockchip_mmc_set_phase,
};
#define to_rockchip_mmc_clock(x) \
container_of(x, struct rockchip_mmc_clock, clk_rate_change_nb)
static int rockchip_mmc_clk_rate_notify(struct notifier_block *nb,
unsigned long event, void *data)
{
struct rockchip_mmc_clock *mmc_clock = to_rockchip_mmc_clock(nb);
struct clk_notifier_data *ndata = data;
/*
* rockchip_mmc_clk is mostly used by mmc controllers to sample
* the intput data, which expects the fixed phase after the tuning
* process. However if the clock rate is changed, the phase is stale
* and may break the data sampling. So here we try to restore the phase
* for that case, except that
* (1) cached_phase is invaild since we inevitably cached it when the
* clock provider be reparented from orphan to its real parent in the
* first place. Otherwise we may mess up the initialization of MMC cards
* since we only set the default sample phase and drive phase later on.
* (2) the new coming rate is higher than the older one since mmc driver
* set the max-frequency to match the boards' ability but we can't go
* over the heads of that, otherwise the tests smoke out the issue.
*/
if (ndata->old_rate <= ndata->new_rate)
return NOTIFY_DONE;
if (event == PRE_RATE_CHANGE)
mmc_clock->cached_phase =
rockchip_mmc_get_phase(&mmc_clock->hw);
else if (mmc_clock->cached_phase != -EINVAL &&
event == POST_RATE_CHANGE)
rockchip_mmc_set_phase(&mmc_clock->hw, mmc_clock->cached_phase);
return NOTIFY_DONE;
}
struct clk *rockchip_clk_register_mmc(const char *name,
const char *const *parent_names, u8 num_parents,
void __iomem *reg, int shift)
{
struct clk_init_data init;
struct rockchip_mmc_clock *mmc_clock;
struct clk *clk;
int ret;
mmc_clock = kmalloc(sizeof(*mmc_clock), GFP_KERNEL);
if (!mmc_clock)
return ERR_PTR(-ENOMEM);
init.name = name;
init.flags = 0;
init.num_parents = num_parents;
init.parent_names = parent_names;
init.ops = &rockchip_mmc_clk_ops;
mmc_clock->hw.init = &init;
mmc_clock->reg = reg;
mmc_clock->shift = shift;
clk = clk_register(NULL, &mmc_clock->hw);
if (IS_ERR(clk)) {
ret = PTR_ERR(clk);
goto err_register;
}
mmc_clock->clk_rate_change_nb.notifier_call =
&rockchip_mmc_clk_rate_notify;
ret = clk_notifier_register(clk, &mmc_clock->clk_rate_change_nb);
if (ret)
goto err_notifier;
return clk;
err_notifier:
clk_unregister(clk);
err_register:
kfree(mmc_clock);
return ERR_PTR(ret);
}
