/*
* simple driver for PWM (Pulse Width Modulator) controller
*
* 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.
*
* Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pwm.h>
#include <mach/hardware.h>
/* i.MX1 and i.MX21 share the same PWM function block: */
#define MX1_PWMC 0x00 /* PWM Control Register */
#define MX1_PWMS 0x04 /* PWM Sample Register */
#define MX1_PWMP 0x08 /* PWM Period Register */
/* i.MX27, i.MX31, i.MX35 share the same PWM function block: */
#define MX3_PWMCR 0x00 /* PWM Control Register */
#define MX3_PWMSAR 0x0C /* PWM Sample Register */
#define MX3_PWMPR 0x10 /* PWM Period Register */
#define MX3_PWMCR_PRESCALER(x) (((x - 1) & 0xFFF) << 4)
#define MX3_PWMCR_DOZEEN (1 << 24)
#define MX3_PWMCR_WAITEN (1 << 23)
#define MX3_PWMCR_DBGEN (1 << 22)
#define MX3_PWMCR_CLKSRC_IPG_HIGH (2 << 16)
#define MX3_PWMCR_CLKSRC_IPG (1 << 16)
#define MX3_PWMCR_EN (1 << 0)
struct imx_chip {
struct clk *clk;
int clk_enabled;
void __iomem *mmio_base;
struct pwm_chip chip;
};
#define to_imx_chip(chip) container_of(chip, struct imx_chip, chip)
static int imx_pwm_config(struct pwm_chip *chip,
struct pwm_device *pwm, int duty_ns, int period_ns)
{
struct imx_chip *imx = to_imx_chip(chip);
if (!(cpu_is_mx1() || cpu_is_mx21())) {
unsigned long long c;
unsigned long period_cycles, duty_cycles, prescale;
u32 cr;
c = clk_get_rate(imx->clk);
c = c * period_ns;
do_div(c, 1000000000);
period_cycles = c;
prescale = period_cycles / 0x10000 + 1;
period_cycles /= prescale;
c = (unsigned long long)period_cycles * duty_ns;
do_div(c, period_ns);
duty_cycles = c;
/*
* according to imx pwm RM, the real period value should be
* PERIOD value in PWMPR plus 2.
*/
if (period_cycles > 2)
period_cycles -= 2;
else
period_cycles = 0;
writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
writel(period_cycles, imx->mmio_base + MX3_PWMPR);
cr = MX3_PWMCR_PRESCALER(prescale) |
MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
MX3_PWMCR_DBGEN | MX3_PWMCR_EN;
if (cpu_is_mx25())
cr |= MX3_PWMCR_CLKSRC_IPG;
else
cr |= MX3_PWMCR_CLKSRC_IPG_HIGH;
writel(cr, imx->mmio_base + MX3_PWMCR);
} else if (cpu_is_mx1() || cpu_is_mx21()) {
/* The PWM subsystem allows for exact frequencies. However,
* I cannot connect a scope on my device to the PWM line and
* thus cannot provide the program the PWM controller
* exactly. Instead, I'm relying on the fact that the
* Bootloader (u-boot or WinCE+haret) has programmed the PWM
* function group already. So I'll just modify the PWM sample
* register to follow the ratio of duty_ns vs. period_ns
* accordingly.
*
* This is good enough for programming the brightness of
* the LCD backlight.
*
* The real implementation would divide PERCLK[0] first by
* both the prescaler (/1 .. /128) and then by CLKSEL
* (/2 .. /16).
*/
u32 max = readl(imx->mmio_base + MX1_PWMP);
u32 p = max * duty_ns / period_ns;
writel(max - p, imx->mmio_base + MX1_PWMS);
} else {
BUG();
}
return 0;
}
static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct imx_chip *imx = to_imx_chip(chip);
int rc = 0;
if (!imx->clk_enabled) {
rc = clk_prepare_enable(imx->clk);
if (!rc)
imx->clk_enabled = 1;
}
return rc;
}
static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct imx_chip *imx = to_imx_chip(chip);
writel(0, imx->mmio_base + MX3_PWMCR);
if (imx->clk_enabled) {
clk_disable_unprepare(imx->clk);
imx->clk_enabled = 0;
}
}
static struct pwm_ops imx_pwm_ops = {
.enable = imx_pwm_enable,
.disable = imx_pwm_disable,
.config = imx_pwm_config,
.owner = THIS_MODULE,
};
static int __devinit imx_pwm_probe(struct platform_device *pdev)
{
struct imx_chip *imx;
struct resource *r;
int ret = 0;
imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
if (imx == NULL) {
dev_err(&pdev->dev, "failed to allocate memory\n");
return -ENOMEM;
}
imx->clk = devm_clk_get(&pdev->dev, "pwm");
if (IS_ERR(imx->clk))
return PTR_ERR(imx->clk);
imx->chip.ops = &imx_pwm_ops;
imx->chip.dev = &pdev->dev;
imx->chip.base = -1;
imx->chip.npwm = 1;
imx->clk_enabled = 0;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (r == NULL) {
dev_err(&pdev->dev, "no memory resource defined\n");
return -ENODEV;
}
imx->mmio_base = devm_request_and_ioremap(&pdev->dev, r);
if (imx->mmio_base == NULL)
return -EADDRNOTAVAIL;
ret = pwmchip_add(&imx->chip);
if (ret < 0)
return ret;
platform_set_drvdata(pdev, imx);
return 0;
}
static int __devexit imx_pwm_remove(struct platform_device *pdev)
{
struct imx_chip *imx;
imx = platform_get_drvdata(pdev);
if (imx == NULL)
return -ENODEV;
return pwmchip_remove(&imx->chip);
}
static struct platform_driver imx_pwm_driver = {
.driver = {
.name = "mxc_pwm",
},
.probe = imx_pwm_probe,
.remove = __devexit_p(imx_pwm_remove),
};
static int __init imx_pwm_init(void)
{
return platform_driver_register(&imx_pwm_driver);
}
arch_initcall(imx_pwm_init);
static void __exit imx_pwm_exit(void)
{
platform_driver_unregister(&imx_pwm_driver);
}
module_exit(imx_pwm_exit);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
