mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-06 02:50:43 +00:00
![Uwe Kleine-König](/assets/img/avatar_default.png)
To eventually get rid of all legacy drivers convert this driver to the modern world implementing .apply(). This just pushes down a slightly optimized variant of how legacy drivers are handled in the core. As a side effect this improves the behaviour for big duty cycles where max * duty_ns overflowed before. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
198 lines
4.7 KiB
C
198 lines
4.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* simple driver for PWM (Pulse Width Modulator) controller
|
|
*
|
|
* Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
|
|
*/
|
|
|
|
#include <linux/bitfield.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/clk.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/err.h>
|
|
#include <linux/io.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/of.h>
|
|
#include <linux/of_device.h>
|
|
#include <linux/platform_device.h>
|
|
#include <linux/pwm.h>
|
|
#include <linux/slab.h>
|
|
|
|
#define MX1_PWMC 0x00 /* PWM Control Register */
|
|
#define MX1_PWMS 0x04 /* PWM Sample Register */
|
|
#define MX1_PWMP 0x08 /* PWM Period Register */
|
|
|
|
#define MX1_PWMC_EN BIT(4)
|
|
|
|
struct pwm_imx1_chip {
|
|
struct clk *clk_ipg;
|
|
struct clk *clk_per;
|
|
void __iomem *mmio_base;
|
|
struct pwm_chip chip;
|
|
};
|
|
|
|
#define to_pwm_imx1_chip(chip) container_of(chip, struct pwm_imx1_chip, chip)
|
|
|
|
static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip)
|
|
{
|
|
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
|
|
int ret;
|
|
|
|
ret = clk_prepare_enable(imx->clk_ipg);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = clk_prepare_enable(imx->clk_per);
|
|
if (ret) {
|
|
clk_disable_unprepare(imx->clk_ipg);
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip)
|
|
{
|
|
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
|
|
|
|
clk_disable_unprepare(imx->clk_per);
|
|
clk_disable_unprepare(imx->clk_ipg);
|
|
}
|
|
|
|
static int pwm_imx1_config(struct pwm_chip *chip,
|
|
struct pwm_device *pwm, u64 duty_ns, u64 period_ns)
|
|
{
|
|
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
|
|
u32 max, p;
|
|
|
|
/*
|
|
* 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).
|
|
*/
|
|
max = readl(imx->mmio_base + MX1_PWMP);
|
|
p = mul_u64_u64_div_u64(max, duty_ns, period_ns);
|
|
|
|
writel(max - p, imx->mmio_base + MX1_PWMS);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int pwm_imx1_enable(struct pwm_chip *chip, struct pwm_device *pwm)
|
|
{
|
|
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
|
|
u32 value;
|
|
int ret;
|
|
|
|
ret = pwm_imx1_clk_prepare_enable(chip);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
value = readl(imx->mmio_base + MX1_PWMC);
|
|
value |= MX1_PWMC_EN;
|
|
writel(value, imx->mmio_base + MX1_PWMC);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void pwm_imx1_disable(struct pwm_chip *chip, struct pwm_device *pwm)
|
|
{
|
|
struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
|
|
u32 value;
|
|
|
|
value = readl(imx->mmio_base + MX1_PWMC);
|
|
value &= ~MX1_PWMC_EN;
|
|
writel(value, imx->mmio_base + MX1_PWMC);
|
|
|
|
pwm_imx1_clk_disable_unprepare(chip);
|
|
}
|
|
|
|
static int pwm_imx1_apply(struct pwm_chip *chip, struct pwm_device *pwm,
|
|
const struct pwm_state *state)
|
|
{
|
|
int err;
|
|
|
|
if (state->polarity != PWM_POLARITY_NORMAL)
|
|
return -EINVAL;
|
|
|
|
if (!state->enabled) {
|
|
if (pwm->state.enabled)
|
|
pwm_imx1_disable(chip, pwm);
|
|
|
|
return 0;
|
|
}
|
|
|
|
err = pwm_imx1_config(chip, pwm, state->duty_cycle, state->period);
|
|
if (err)
|
|
return err;
|
|
|
|
if (!pwm->state.enabled)
|
|
return pwm_imx1_enable(chip, pwm);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct pwm_ops pwm_imx1_ops = {
|
|
.apply = pwm_imx1_apply,
|
|
.owner = THIS_MODULE,
|
|
};
|
|
|
|
static const struct of_device_id pwm_imx1_dt_ids[] = {
|
|
{ .compatible = "fsl,imx1-pwm", },
|
|
{ /* sentinel */ }
|
|
};
|
|
MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids);
|
|
|
|
static int pwm_imx1_probe(struct platform_device *pdev)
|
|
{
|
|
struct pwm_imx1_chip *imx;
|
|
|
|
imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
|
|
if (!imx)
|
|
return -ENOMEM;
|
|
|
|
imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
|
|
if (IS_ERR(imx->clk_ipg))
|
|
return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_ipg),
|
|
"getting ipg clock failed\n");
|
|
|
|
imx->clk_per = devm_clk_get(&pdev->dev, "per");
|
|
if (IS_ERR(imx->clk_per))
|
|
return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_per),
|
|
"failed to get peripheral clock\n");
|
|
|
|
imx->chip.ops = &pwm_imx1_ops;
|
|
imx->chip.dev = &pdev->dev;
|
|
imx->chip.npwm = 1;
|
|
|
|
imx->mmio_base = devm_platform_ioremap_resource(pdev, 0);
|
|
if (IS_ERR(imx->mmio_base))
|
|
return PTR_ERR(imx->mmio_base);
|
|
|
|
return devm_pwmchip_add(&pdev->dev, &imx->chip);
|
|
}
|
|
|
|
static struct platform_driver pwm_imx1_driver = {
|
|
.driver = {
|
|
.name = "pwm-imx1",
|
|
.of_match_table = pwm_imx1_dt_ids,
|
|
},
|
|
.probe = pwm_imx1_probe,
|
|
};
|
|
module_platform_driver(pwm_imx1_driver);
|
|
|
|
MODULE_LICENSE("GPL v2");
|
|
MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
|