Re: [PATCH v9 1/2] pwm: add support for atmel-hlcdc-pwm device

[Nicolas Ferre <nicolas.ferre@atmel.com>]

On 07/10/2014 12:14, Boris Brezillon :
> The HLCDC IP available in some Atmel SoCs (i.e. sam9x5i.e. at91sam9n12,

What is this sam9x5i.e. ? I would say instead:

The HLCDC IP available in some Atmel SoCs (i.e. at91sam9x5, at91sam9n12
or sama5d3 families for instance) provides a PWM device.

> at91sam9x5 family or sama5d3 family) provide a PWM device.
> 
> This driver add support for a PWM chip exposing a single PWM device (which
> will most likely be used to drive a backlight device).
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> Tested-by: Anthony Harivel <anthony.harivel@emtrion.de>
> Tested-by: Ludovic Desroches <ludovic.desroches@atmel.com>
> Acked-by: Thierry Reding <thierry.reding@gmail.com>

See the little nitpicking...

But otherwise:
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

> ---
>  drivers/pwm/Kconfig           |   9 ++
>  drivers/pwm/Makefile          |   1 +
>  drivers/pwm/pwm-atmel-hlcdc.c | 259 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 269 insertions(+)
>  create mode 100644 drivers/pwm/pwm-atmel-hlcdc.c
> 
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index b800783..c36f308 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -50,6 +50,15 @@ config PWM_ATMEL
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called pwm-atmel.
>  
> +config PWM_ATMEL_HLCDC_PWM
> +	tristate "Atmel HLCDC PWM support"
> +	select MFD_ATMEL_HLCDC
> +	help
> +	  Generic PWM framework driver for Atmel HLCDC PWM.

What about:
"Generic PWM framework driver for the PWM output of the HLCDC (Atmel
High-end LCD Controller). This PWM output is mainly used to control the
LCD backlight.

> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called pwm-atmel-hlcdc.
> +
>  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 f8c577d..eb0aae5 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -2,6 +2,7 @@ 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-$(CONFIG_PWM_ATMEL_HLCDC_PWM)	+= pwm-atmel-hlcdc.o
>  obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
>  obj-$(CONFIG_PWM_BCM_KONA)	+= pwm-bcm-kona.o
>  obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
> diff --git a/drivers/pwm/pwm-atmel-hlcdc.c b/drivers/pwm/pwm-atmel-hlcdc.c
> new file mode 100644
> index 0000000..eaf8b12
> --- /dev/null
> +++ b/drivers/pwm/pwm-atmel-hlcdc.c
> @@ -0,0 +1,259 @@
> +/*
> + * Copyright (C) 2014 Free Electrons
> + * Copyright (C) 2014 Atmel
> + *
> + * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
> + *
> + * 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.
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/mfd/atmel-hlcdc.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>
> +#include <linux/regmap.h>
> +
> +#define ATMEL_HLCDC_PWMCVAL_MASK	GENMASK(15, 8)
> +#define ATMEL_HLCDC_PWMCVAL(x)		(((x) << 8) & ATMEL_HLCDC_PWMCVAL_MASK)
> +#define ATMEL_HLCDC_PWMPOL		BIT(4)
> +#define ATMEL_HLCDC_PWMPS_MASK		GENMASK(2, 0)
> +#define ATMEL_HLCDC_PWMPS_MAX		0x6
> +#define ATMEL_HLCDC_PWMPS(x)		((x) & ATMEL_HLCDC_PWMPS_MASK)
> +
> +struct atmel_hlcdc_pwm {
> +	struct pwm_chip chip;
> +	struct atmel_hlcdc *hlcdc;
> +	struct clk *cur_clk;
> +};
> +
> +static inline struct atmel_hlcdc_pwm *to_atmel_hlcdc_pwm(struct pwm_chip *chip)
> +{
> +	return container_of(chip, struct atmel_hlcdc_pwm, chip);
> +}
> +
> +static int atmel_hlcdc_pwm_config(struct pwm_chip *c,
> +				  struct pwm_device *pwm,
> +				  int duty_ns, int period_ns)
> +{
> +	struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
> +	struct atmel_hlcdc *hlcdc = chip->hlcdc;
> +	struct clk *new_clk = hlcdc->slow_clk;
> +	u64 pwmcval = duty_ns * 256;
> +	unsigned long clk_freq;
> +	u64 clk_period_ns;
> +	u32 pwmcfg;
> +	int pres;
> +
> +	clk_freq = clk_get_rate(new_clk);
> +	clk_period_ns = (u64)NSEC_PER_SEC * 256;
> +	do_div(clk_period_ns, clk_freq);
> +
> +	if (clk_period_ns > period_ns) {
> +		new_clk = hlcdc->sys_clk;
> +		clk_freq = clk_get_rate(new_clk);
> +		clk_period_ns = (u64)NSEC_PER_SEC * 256;
> +		do_div(clk_period_ns, clk_freq);
> +	}
> +
> +	for (pres = 0; pres <= ATMEL_HLCDC_PWMPS_MAX; pres++)
> +		if ((clk_period_ns << pres) >= period_ns)
> +			break;
> +
> +	if (pres > ATMEL_HLCDC_PWMPS_MAX)
> +		return -EINVAL;
> +
> +	pwmcfg = ATMEL_HLCDC_PWMPS(pres);
> +
> +	if (new_clk != chip->cur_clk) {
> +		u32 gencfg = 0;
> +		int ret;
> +
> +		ret = clk_prepare_enable(new_clk);
> +		if (ret)
> +			return ret;
> +
> +		clk_disable_unprepare(chip->cur_clk);
> +		chip->cur_clk = new_clk;
> +
> +		if (new_clk == hlcdc->sys_clk)
> +			gencfg = ATMEL_HLCDC_CLKPWMSEL;
> +
> +		ret = regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(0),
> +					 ATMEL_HLCDC_CLKPWMSEL, gencfg);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	do_div(pwmcval, period_ns);
> +
> +	/*
> +	 * The PWM duty cycle is configurable from 0/256 to 255/256 of the
> +	 * period cycle. Hence we can't set a duty cycle occupying the
> +	 * whole period cycle if we're asked to.
> +	 * Set it to 255 if pwmcval is greater than 256.
> +	 */
> +	if (pwmcval > 255)
> +		pwmcval = 255;
> +
> +	pwmcfg |= ATMEL_HLCDC_PWMCVAL(pwmcval);
> +
> +	return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
> +				  ATMEL_HLCDC_PWMCVAL_MASK |
> +				  ATMEL_HLCDC_PWMPS_MASK,
> +				  pwmcfg);
> +}
> +
> +static int atmel_hlcdc_pwm_set_polarity(struct pwm_chip *c,
> +					struct pwm_device *pwm,
> +					enum pwm_polarity polarity)
> +{
> +	struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
> +	struct atmel_hlcdc *hlcdc = chip->hlcdc;
> +	u32 cfg = 0;
> +
> +	if (polarity == PWM_POLARITY_NORMAL)
> +		cfg = ATMEL_HLCDC_PWMPOL;
> +
> +	return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
> +				  ATMEL_HLCDC_PWMPOL, cfg);
> +}
> +
> +static int atmel_hlcdc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
> +{
> +	struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
> +	struct atmel_hlcdc *hlcdc = chip->hlcdc;
> +	u32 status;
> +	int ret;
> +
> +	ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_EN, ATMEL_HLCDC_PWM);
> +	if (ret)
> +		return ret;
> +
> +	while (true) {
> +		ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
> +		if (ret)
> +			return ret;
> +
> +		if ((status & ATMEL_HLCDC_PWM) != 0)
> +			break;
> +
> +		usleep_range(1, 10);
> +	}
> +
> +	return 0;
> +}
> +
> +static void atmel_hlcdc_pwm_disable(struct pwm_chip *c,
> +				    struct pwm_device *pwm)
> +{
> +	struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
> +	struct atmel_hlcdc *hlcdc = chip->hlcdc;
> +	u32 status;
> +	int ret;
> +
> +	ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_DIS, ATMEL_HLCDC_PWM);
> +	if (ret)
> +		return;
> +
> +	while (true) {
> +		ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
> +		if (ret)
> +			return;
> +
> +		if ((status & ATMEL_HLCDC_PWM) == 0)
> +			break;
> +
> +		usleep_range(1, 10);
> +	}
> +}
> +
> +static const struct pwm_ops atmel_hlcdc_pwm_ops = {
> +	.config = atmel_hlcdc_pwm_config,
> +	.set_polarity = atmel_hlcdc_pwm_set_polarity,
> +	.enable = atmel_hlcdc_pwm_enable,
> +	.disable = atmel_hlcdc_pwm_disable,
> +	.owner = THIS_MODULE,
> +};
> +
> +static int atmel_hlcdc_pwm_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct atmel_hlcdc_pwm *chip;
> +	struct atmel_hlcdc *hlcdc;
> +	int ret;
> +
> +	hlcdc = dev_get_drvdata(dev->parent);
> +
> +	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	ret = clk_prepare_enable(hlcdc->periph_clk);
> +	if (ret)
> +		return ret;
> +
> +	chip->hlcdc = hlcdc;
> +	chip->chip.ops = &atmel_hlcdc_pwm_ops;
> +	chip->chip.dev = dev;
> +	chip->chip.base = -1;
> +	chip->chip.npwm = 1;
> +	chip->chip.of_xlate = of_pwm_xlate_with_flags;
> +	chip->chip.of_pwm_n_cells = 3;
> +	chip->chip.can_sleep = 1;
> +
> +	ret = pwmchip_add(&chip->chip);
> +	if (ret) {
> +		clk_disable_unprepare(hlcdc->periph_clk);
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, chip);
> +
> +	return 0;
> +}
> +
> +static int atmel_hlcdc_pwm_remove(struct platform_device *pdev)
> +{
> +	struct atmel_hlcdc_pwm *chip = platform_get_drvdata(pdev);
> +	int ret;
> +
> +	ret = pwmchip_remove(&chip->chip);
> +	if (ret)
> +		return ret;
> +
> +	clk_disable_unprepare(chip->hlcdc->periph_clk);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id atmel_hlcdc_pwm_dt_ids[] = {
> +	{ .compatible = "atmel,hlcdc-pwm" },
> +	{ /* sentinel */ },
> +};
> +
> +static struct platform_driver atmel_hlcdc_pwm_driver = {
> +	.driver = {
> +		.name = "atmel-hlcdc-pwm",
> +		.of_match_table = atmel_hlcdc_pwm_dt_ids,
> +	},
> +	.probe = atmel_hlcdc_pwm_probe,
> +	.remove = atmel_hlcdc_pwm_remove,
> +};
> +module_platform_driver(atmel_hlcdc_pwm_driver);
> +
> +MODULE_ALIAS("platform:atmel-hlcdc-pwm");
> +MODULE_AUTHOR("Boris Brezillon <boris.brezillon@free-electrons.com>");
> +MODULE_DESCRIPTION("Atmel HLCDC PWM driver");
> +MODULE_LICENSE("GPL v2");
> 


-- 
Nicolas Ferre