pwm-mxs.c
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/*
* Copyright 2012 Freescale Semiconductor, Inc.
*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#include <linux/stmp_device.h>
#define SET 0x4
#define CLR 0x8
#define TOG 0xc
#define PWM_CTRL 0x0
#define PWM_ACTIVE0 0x10
#define PWM_PERIOD0 0x20
#define PERIOD_PERIOD(p) ((p) & 0xffff)
#define PERIOD_PERIOD_MAX 0x10000
#define PERIOD_ACTIVE_HIGH (3 << 16)
#define PERIOD_INACTIVE_LOW (2 << 18)
#define PERIOD_CDIV(div) (((div) & 0x7) << 20)
#define PERIOD_CDIV_MAX 8
struct mxs_pwm_chip {
struct pwm_chip chip;
struct clk *clk;
void __iomem *base;
};
#define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
int ret, div = 0;
unsigned int period_cycles, duty_cycles;
unsigned long rate;
unsigned long long c;
rate = clk_get_rate(mxs->clk);
while (1) {
c = rate / (1 << div);
c = c * period_ns;
do_div(c, 1000000000);
if (c < PERIOD_PERIOD_MAX)
break;
div++;
if (div > PERIOD_CDIV_MAX)
return -EINVAL;
}
period_cycles = c;
c *= duty_ns;
do_div(c, period_ns);
duty_cycles = c;
/*
* If the PWM channel is disabled, make sure to turn on the clock
* before writing the register. Otherwise, keep it enabled.
*/
if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
ret = clk_prepare_enable(mxs->clk);
if (ret)
return ret;
}
writel(duty_cycles << 16,
mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH |
PERIOD_INACTIVE_LOW | PERIOD_CDIV(div),
mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
/*
* If the PWM is not enabled, turn the clock off again to save power.
*/
if (!test_bit(PWMF_ENABLED, &pwm->flags))
clk_disable_unprepare(mxs->clk);
return 0;
}
static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
int ret;
ret = clk_prepare_enable(mxs->clk);
if (ret)
return ret;
writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
return 0;
}
static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
clk_disable_unprepare(mxs->clk);
}
static const struct pwm_ops mxs_pwm_ops = {
.config = mxs_pwm_config,
.enable = mxs_pwm_enable,
.disable = mxs_pwm_disable,
.owner = THIS_MODULE,
};
static int mxs_pwm_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct mxs_pwm_chip *mxs;
struct resource *res;
int ret;
mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL);
if (!mxs)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
mxs->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(mxs->base))
return PTR_ERR(mxs->base);
mxs->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(mxs->clk))
return PTR_ERR(mxs->clk);
mxs->chip.dev = &pdev->dev;
mxs->chip.ops = &mxs_pwm_ops;
mxs->chip.base = -1;
ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
if (ret < 0) {
dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
return ret;
}
ret = pwmchip_add(&mxs->chip);
if (ret < 0) {
dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
return ret;
}
platform_set_drvdata(pdev, mxs);
ret = stmp_reset_block(mxs->base);
if (ret)
goto pwm_remove;
return 0;
pwm_remove:
pwmchip_remove(&mxs->chip);
return ret;
}
static int mxs_pwm_remove(struct platform_device *pdev)
{
struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev);
return pwmchip_remove(&mxs->chip);
}
static const struct of_device_id mxs_pwm_dt_ids[] = {
{ .compatible = "fsl,imx23-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);
static struct platform_driver mxs_pwm_driver = {
.driver = {
.name = "mxs-pwm",
.owner = THIS_MODULE,
.of_match_table = mxs_pwm_dt_ids,
},
.probe = mxs_pwm_probe,
.remove = mxs_pwm_remove,
};
module_platform_driver(mxs_pwm_driver);
MODULE_ALIAS("platform:mxs-pwm");
MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
MODULE_DESCRIPTION("Freescale MXS PWM Driver");
MODULE_LICENSE("GPL v2");