Subject: [PATCH v6 1/2] PWM: atmel-pwm: add PWM controller driver

From: [email-masked] (Bo Shen)
Date: Thu, 14 Nov 2013 14:28:36 +0800

Hi J,

On 11/13/2013 05:56 PM, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 15:59 Fri 01 Nov     , Bo Shen wrote:
>> Add Atmel PWM controller driver based on PWM framework.
>>
>> This is the basic function implementation of Atmel PWM controller.
>> It can work with PWM based led and backlight.
>>
>> Signed-off-by: Bo Shen <[email-masked]>
>>
>> ---
>> Changes in v6:
>>    - using relaxed version for writel and readl
>>    - add none device tree support
>>    - change some define from lower case to upper case
>>    - split device tree binding document as a separate patch
>>
>> Changes in v5:
>>    - call clk_disable directly, if so, it won't cause more than one channel
>>      enabled, the clock can not be disabled.
>>
>> Changes in v4:
>>    - check the return value of clk_prepare()
>>    - change channel register size as constant
>>
>> Changes in v3:
>>    - change compatible string from "atmel,sama5-pwm" to "atmel,sama5d3-pwm"
>>    - Add PWM led example in binding documentation
>>    - Using micro replace hard code
>>
>> Changes in v2:
>>    - Address the comments from Thierry Reding
>>
>>   drivers/pwm/Kconfig     |    9 ++
>>   drivers/pwm/Makefile    |    1 +
>>   drivers/pwm/pwm-atmel.c |  360 +++++++++++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 370 insertions(+)
>>   create mode 100644 drivers/pwm/pwm-atmel.c
>>
>> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
>> index 75840b5..54237b9 100644
>> --- a/drivers/pwm/Kconfig
>> +++ b/drivers/pwm/Kconfig
>> @@ -41,6 +41,15 @@ config PWM_AB8500
>>   	  To compile this driver as a module, choose M here: the module
>>   	  will be called pwm-ab8500.
>>
>> +config PWM_ATMEL
>> +	tristate "Atmel PWM support"
>> +	depends on ARCH_AT91
>> +	help
>> +	  Generic PWM framework driver for Atmel SoC.
>> +
>> +	  To compile this driver as a module, choose M here: the module
>> +	  will be called pwm-atmel.
>> +
>>   config PWM_ATMEL_TCB
>>   	tristate "Atmel TC Block PWM support"
>>   	depends on ATMEL_TCLIB && OF
>> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
>> index 77a8c18..5b193f8 100644
>> --- a/drivers/pwm/Makefile
>> +++ b/drivers/pwm/Makefile
>> @@ -1,6 +1,7 @@
>>   obj-$(CONFIG_PWM)		+= core.o
>>   obj-$(CONFIG_PWM_SYSFS)		+= sysfs.o
>>   obj-$(CONFIG_PWM_AB8500)	+= pwm-ab8500.o
>> +obj-$(CONFIG_PWM_ATMEL)		+= pwm-atmel.o
>>   obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
>>   obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
>>   obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
>> diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c
>> new file mode 100644
>> index 0000000..ac54252
>> --- /dev/null
>> +++ b/drivers/pwm/pwm-atmel.c
>> @@ -0,0 +1,360 @@
>> +/*
>> + * Driver for Atmel Pulse Width Modulation Controller
>> + *
>> + * Copyright (C) 2013 Atmel Corporation
>> + *		 Bo Shen <[email-masked]>
>> + *
>> + * Licensed under GPLv2.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/err.h>
>> +#include <linux/io.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>
>> +
>> +/* The following is global registers for PWM controller */
>> +#define PWM_ENA			0x04
>> +#define PWM_DIS			0x08
>> +#define PWM_SR			0x0C
>> +/* bit field in SR */
>> +#define PWM_SR_ALL_CH_ON	0x0F
>> +
>> +/* The following register is PWM channel related registers */
>> +#define PWM_CH_REG_OFFSET	0x200
>> +#define PWM_CH_REG_SIZE		0x20
>> +
>> +#define PWM_CMR			0x0
>> +/* bit field in CMR */
>> +#define PWM_CMR_CPOL		(1 << 9)
>> +#define PWM_CMR_UPD_CDTY	(1 << 10)
>> +
>> +/* The following registers for PWM v1 */
>> +#define PWMV1_CDTY		0x04
>> +#define PWMV1_CPRD		0x08
>> +#define PWMV1_CUPD		0x10
>> +
>> +/* The following registers for PWM v2 */
>> +#define PWMV2_CDTY		0x04
>> +#define PWMV2_CDTYUPD		0x08
>> +#define PWMV2_CPRD		0x0C
>> +#define PWMV2_CPRDUPD		0x10
>> +
>> +/* max value for duty and period */
>> +/*
>> + * Although the duty and period register is 32 bit,
>> + * however only the LSB 16 bits are significant.
>> + */
>> +#define PWM_MAX_DTY		0xFFFF
>> +#define PWM_MAX_PRD		0xFFFF
>> +#define PRD_MAX_PRES		10
>> +
>> +struct atmel_pwm_chip {
>> +	struct pwm_chip chip;
>> +	struct clk *clk;
>> +	void __iomem *base;
>> +
>> +	void (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
>> +		       int dty, int prd);
>> +};
>> +
>> +static inline struct atmel_pwm_chip *to_atmel_pwm_chip(struct pwm_chip *chip)
>> +{
>> +	return container_of(chip, struct atmel_pwm_chip, chip);
>> +}
>> +
>> +static inline u32 atmel_pwm_readl(struct atmel_pwm_chip *chip,
>> +				  unsigned long offset)
>> +{
>> +	return readl_relaxed(chip->base + offset);
>> +}
>> +
>> +static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip,
>> +				    unsigned long offset, unsigned long val)
>> +{
>> +	writel_relaxed(val, chip->base + offset);
>> +}
>> +
>> +static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip,
>> +				     unsigned int ch, unsigned long offset)
>> +{
>> +	return readl_relaxed(chip->base + PWM_CH_REG_OFFSET +
>> +			ch * PWM_CH_REG_SIZE + offset);
>> +}
>> +
>> +static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip,
>> +				       unsigned int ch, unsigned long offset,
>> +				       unsigned long val)
>> +{
>> +	writel_relaxed(val, chip->base + PWM_CH_REG_OFFSET +
>> +			ch * PWM_CH_REG_SIZE + offset);
>> +}
>> +
>> +static int atmel_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>> +		int duty_ns, int period_ns)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +	unsigned long clk_rate, prd, dty;
>> +	unsigned long long div;
>> +	int ret, pres = 0;
>> +
>> +	clk_rate = clk_get_rate(atmel_pwm->clk);
>> +	div = clk_rate;
>> +
>> +	/* Calculate the period cycles */
>> +	while (div > PWM_MAX_PRD) {
>> +		div = clk_rate / (1 << pres);
>> +		div = div * period_ns;
>> +		/* 1/Hz = 100000000 ns */
>> +		do_div(div, 1000000000);
>> +
>> +		if (pres++ > PRD_MAX_PRES) {
>> +			pr_err("PRES is bigger than maximum pre-scaler\n");
>> +			return -EINVAL;
>> +		}
>> +	}
>> +
>> +	/* Calculate the duty cycles */
>> +	prd = div;
>> +	div *= duty_ns;
>> +	do_div(div, period_ns);
>> +	dty = div;
>> +
>> +	ret = clk_enable(atmel_pwm->clk);
>> +	if (ret) {
>> +		pr_err("Failed to enable pwm clock\n");
>> +		return ret;
>> +	}
>> +
>> +	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, pres);
>> +	atmel_pwm->config(chip, pwm, dty, prd);
>> +
>> +	clk_disable(atmel_pwm->clk);
>> +
>> +	return 0;
>> +}
>> +
>> +static void atmel_pwm_config_v1(struct pwm_chip *chip, struct pwm_device *pwm,
>> +				int dty, int prd)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +	unsigned int val;
>> +
>> +	/*
>> +	 * If the PWM channel is disabled, write value to duty and period
>> +	 * registers directly.
>> +	 * If the PWM channel is enabled, using the update register, it needs
>> +	 * to set bit 10 of CMR to 0
>> +	 */
>> +	if (test_bit(PWMF_ENABLED, &pwm->flags)) {
>> +		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CUPD, dty);
>> +
>> +		val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
>> +		val &= ~PWM_CMR_UPD_CDTY;
>> +		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
>> +	} else {
>> +		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CDTY, dty);
>> +		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV1_CPRD, prd);
>> +	}
>> +}
>> +
>> +static void atmel_pwm_config_v2(struct pwm_chip *chip, struct pwm_device *pwm,
>> +				int dty, int prd)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +
>> +	/*
>> +	 * If the PWM channel is disabled, write value to duty and period
>> +	 * registers directly.
>> +	 * If the PWM channel is enabled, using the duty update register to
>> +	 * update the value.
>> +	 */
>> +	if (test_bit(PWMF_ENABLED, &pwm->flags)) {
>> +		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTYUPD, dty);
>> +	} else {
>> +		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CDTY, dty);
>> +		atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWMV2_CPRD, prd);
>> +	}
>> +}
>> +
>> +static int atmel_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
>> +		enum pwm_polarity polarity)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +	u32 val = 0;
>> +	int ret;
>> +
>> +	if (polarity == PWM_POLARITY_NORMAL)
>> +		val &= ~PWM_CMR_CPOL;
>> +	else
>> +		val |= PWM_CMR_CPOL;
>> +
>> +	ret = clk_enable(atmel_pwm->clk);
>> +	if (ret) {
>> +		pr_err("failed to enable pwm clock\n");
>> +		return ret;
>> +	}
>> +
>> +	atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
>> +
>> +	clk_disable(atmel_pwm->clk);
>> +
>> +	return 0;
>> +}
>> +
>> +static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +	int ret;
>> +
>> +	ret = clk_enable(atmel_pwm->clk);
>> +	if (ret) {
>> +		pr_err("failed to enable pwm clock\n");
>> +		return ret;
>> +	}
>> +
>> +	atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
>> +
>> +	return 0;
>> +}
>> +
>> +static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
>> +
>> +	atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
>> +
>> +	clk_disable(atmel_pwm->clk);
>> +}
>> +
>> +static const struct pwm_ops atmel_pwm_ops = {
>> +	.config = atmel_pwm_config,
>> +	.set_polarity = atmel_pwm_set_polarity,
>> +	.enable = atmel_pwm_enable,
>> +	.disable = atmel_pwm_disable,
>> +	.owner = THIS_MODULE,
>> +};
>> +
>> +struct atmel_pwm_data {
>> +	void (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
>> +		       int dty, int prd);
>> +};
>> +
>> +static const struct atmel_pwm_data atmel_pwm_data_v1 = {
>> +	.config = atmel_pwm_config_v1,
>> +};
>> +
>> +static const struct atmel_pwm_data atmel_pwm_data_v2 = {
>> +	.config = atmel_pwm_config_v2,
>> +};
>> +
>> +static const struct platform_device_id atmel_pwm_devtypes[] = {
>> +	{
>> +		.name = "at91sam9rl-pwm",
>> +		.driver_data = (kernel_ulong_t)&atmel_pwm_data_v1,
>> +	}, {
>> +		.name = "sama5d3-pwm",
>> +		.driver_data = (kernel_ulong_t)&atmel_pwm_data_v2,
>> +	}, {
>> +		/* sentinel */
>> +	},
>> +};
>> +MODULE_DEVICE_TABLE(platform, atmel_pwm_devtypes);
>> +
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id atmel_pwm_dt_ids[] = {
>> +	{
>> +		.compatible = "atmel,at91sam9rl-pwm",
>> +		.data = &atmel_pwm_data_v1,
>> +	}, {
>> +		.compatible = "atmel,sama5d3-pwm",
>> +		.data = &atmel_pwm_data_v2,
>> +	}, {
>> +		/* sentinel */
>> +	},
>> +};
>> +MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);
>> +#endif
>> +
>> +static int atmel_pwm_probe(struct platform_device *pdev)
>> +{
>> +	const struct of_device_id *of_id =
>> +		of_match_device(atmel_pwm_dt_ids, &pdev->dev);
>> +	const struct atmel_pwm_data *data;
>> +	struct atmel_pwm_chip *atmel_pwm;
>> +	struct resource *res;
>> +	int ret;
>> +
>> +	atmel_pwm = devm_kzalloc(&pdev->dev, sizeof(*atmel_pwm), GFP_KERNEL);
>> +	if (!atmel_pwm)
>> +		return -ENOMEM;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	if (!res)
>> +		return -ENODEV;
>> +
>> +	atmel_pwm->base = devm_ioremap_resource(&pdev->dev, res);
>> +	if (IS_ERR(atmel_pwm->base))
>> +		return PTR_ERR(atmel_pwm->base);
>> +
>> +	atmel_pwm->clk = devm_clk_get(&pdev->dev, NULL);
>> +	if (IS_ERR(atmel_pwm->clk))
>> +		return PTR_ERR(atmel_pwm->clk);
>> +
>> +	ret = clk_prepare(atmel_pwm->clk);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "failed to prepare pwm clock\n");
>> +		return ret;
>> +	}
>> +
>> +	atmel_pwm->chip.dev = &pdev->dev;
>> +	atmel_pwm->chip.ops = &atmel_pwm_ops;
> I get one issue here for non-dt platform

I will fix this issue for none-dt in next version.

>> +	atmel_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
>> +	atmel_pwm->chip.of_pwm_n_cells = 3;
> those 3 no need

Which "those 3"?
for dt / none-dt compatible, I will use following code
--->8---
if (pdev->dev.of_node) {
	atmel_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
         atmel_pwm->chip.of_pwm_n_cells = 3;
         atmel_pwm->chip.base = -1;
} else {
	atmel_pwm->chip.base = 0;
}
---8<---

>> +	atmel_pwm->chip.base = -1;
> here we need specify the base from the board so we known which pwn to use
> for DT -1 is good as we use phandle

I will fix this issue for none-dt in next version.

> Best Regards,
> J.
>> +	atmel_pwm->chip.npwm = 4;
>> +
>> +	data = of_id->data;
>> +	atmel_pwm->config = data->config;
>> +
>> +	ret = pwmchip_add(&atmel_pwm->chip);
>> +	if (ret < 0) {
>> +		dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
>> +		goto unprepare_clk;
>> +	}
>> +
>> +	platform_set_drvdata(pdev, atmel_pwm);
>> +
>> +unprepare_clk:
>> +	clk_unprepare(atmel_pwm->clk);
>> +	return ret;
>> +}
>> +
>> +static int atmel_pwm_remove(struct platform_device *pdev)
>> +{
>> +	struct atmel_pwm_chip *atmel_pwm = platform_get_drvdata(pdev);
>> +
>> +	clk_unprepare(atmel_pwm->clk);
>> +
>> +	return pwmchip_remove(&atmel_pwm->chip);
>> +}
>> +
>> +static struct platform_driver atmel_pwm_driver = {
>> +	.driver = {
>> +		.name = "atmel-pwm",
>> +		.of_match_table = of_match_ptr(atmel_pwm_dt_ids),
>> +	},
>> +	.id_table = atmel_pwm_devtypes,
>> +	.probe = atmel_pwm_probe,
>> +	.remove = atmel_pwm_remove,
>> +};
>> +module_platform_driver(atmel_pwm_driver);
>> +
>> +MODULE_ALIAS("platform:atmel-pwm");
>> +MODULE_AUTHOR("Bo Shen <[email-masked]>");
>> +MODULE_DESCRIPTION("Atmel PWM driver");
>> +MODULE_LICENSE("GPL v2");
>> --
>> 1.7.9.5
>>

Best Regards,
Bo Shen