[linux-yocto] [PATCH 18/29] pwm: add support for Intel Low Power Subsystem PWM

[Kamble, Nitin A]

On 4/7/2014 8:18 AM, rebecca.swee.fun.chang at intel.com wrote:
> From: Mika Westerberg <mika.westerberg at linux.intel.com>
>
> Add support for Intel Low Power I/O subsystem PWM controllers found on some
> newer intel chipsets.
>
> Signed-off-by: Mika Westerberg <mika.westerberg at linux.intel.com>
>
> <This patch is pulled from Mika's git tree previousy. The git
> tree is no longer accessible now.>
This git tree status information is not useful in the commit message. 
You can include it
in the pull request email, and drop it from the commit message here.

Nitin

>
> Signed-off-by: Chew, Chiau Ee <chiau.ee.chew at intel.com>
> Signed-off-by: Maurice Petallo <mauricex.r.petallo at intel.com>
> ---
>   drivers/pwm/Kconfig    |   10 +++
>   drivers/pwm/Makefile   |    1 +
>   drivers/pwm/pwm-lpss.c |  183 ++++++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 194 insertions(+)
>   create mode 100644 drivers/pwm/pwm-lpss.c
>
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 14a9122..f2b0948 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -87,6 +87,16 @@ config PWM_LPC32XX
>   	  To compile this driver as a module, choose M here: the module
>   	  will be called pwm-lpc32xx.
>   
> +config PWM_LPSS
> +	tristate "Intel LPSS PWM support"
> +	depends on ACPI
> +	help
> +	  Generic PWM framework driver for Intel Low Power Subsystem PWM
> +	  controller.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called pwm-lpio.
> +
>   config PWM_MXS
>   	tristate "Freescale MXS PWM support"
>   	depends on ARCH_MXS && OF
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index 5aa815f..6a5e723 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -5,6 +5,7 @@ obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
>   obj-$(CONFIG_PWM_IMX)		+= pwm-imx.o
>   obj-$(CONFIG_PWM_JZ4740)	+= pwm-jz4740.o
>   obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
> +obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
>   obj-$(CONFIG_PWM_MXS)		+= pwm-mxs.o
>   obj-$(CONFIG_PWM_PUV3)		+= pwm-puv3.o
>   obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
> diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
> new file mode 100644
> index 0000000..fb3548c
> --- /dev/null
> +++ b/drivers/pwm/pwm-lpss.c
> @@ -0,0 +1,183 @@
> +/*
> + * Intel Low Power Subsystem PWM controller driver
> + *
> + * Copyright (C) 2013, Intel Corporation
> + * Author: Mika Westerberg <mika.westerberg at linux.intel.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.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pwm.h>
> +#include <linux/platform_device.h>
> +
> +#define PWM			0x00000000
> +#define PWM_ENABLE		BIT(31)
> +#define PWM_SW_UPDATE		BIT(30)
> +#define PWM_BASE_UNIT_SHIFT	8
> +#define PWM_BASE_UNIT_MASK	0x00ffff00
> +#define PWM_ON_TIME_DIV_MASK	0x000000ff
> +
> +struct pwm_lpss_chip {
> +	struct pwm_chip chip;
> +	void __iomem *regs;
> +	struct clk *clk;
> +};
> +
> +static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
> +{
> +	return container_of(chip, struct pwm_lpss_chip, chip);
> +}
> +
> +static void pwm_lpss_set_state(struct pwm_lpss_chip *lpwm, bool enable)
> +{
> +	u32 ctrl;
> +
> +	ctrl = readl(lpwm->regs + PWM);
> +	if (enable)
> +		ctrl |= PWM_ENABLE;
> +	else
> +		ctrl &= ~PWM_ENABLE;
> +	writel(ctrl, lpwm->regs + PWM);
> +}
> +
> +static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
> +	int duty_ns, int period_ns)
> +{
> +	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
> +	u8 base_unit_hi, base_unit_lo, on_time_div;
> +	unsigned long c = clk_get_rate(lpwm->clk);
> +	unsigned long hz, cycle_cnt;
> +	u32 ctrl;
> +
> +	hz = 1000000000UL / period_ns;
> +
> +	/*
> +	 * There is no duty cycle resolution if base_unit value is higher
> +	 * than 128.
> +	 */
> +	base_unit_hi = (hz * 256) / c;
> +	if (base_unit_hi > 128)
> +		return -EINVAL;
> +
> +	base_unit_lo = (hz * 65536) / c;
> +	cycle_cnt = base_unit_hi ? 256 / base_unit_hi : 256;
> +
> +	if (duty_ns <= 0)
> +		duty_ns = 1;
> +
> +	on_time_div = cycle_cnt / (period_ns / duty_ns);
> +
> +	ctrl = readl(lpwm->regs + PWM);
> +	ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
> +	ctrl |= (base_unit_hi | base_unit_lo) << PWM_BASE_UNIT_SHIFT;
> +	ctrl |= on_time_div;
> +	/* request PWM to update on next cycle */
> +	ctrl |= PWM_SW_UPDATE;
> +	writel(ctrl, lpwm->regs + PWM);
> +
> +	return 0;
> +}
> +
> +static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
> +
> +	clk_prepare_enable(lpwm->clk);
> +	pwm_lpss_set_state(lpwm, true);
> +	return 0;
> +}
> +
> +static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> +	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
> +
> +	pwm_lpss_set_state(lpwm, false);
> +	clk_disable_unprepare(lpwm->clk);
> +}
> +
> +static const struct pwm_ops pwm_lpss_ops = {
> +	.config = pwm_lpss_config,
> +	.enable = pwm_lpss_enable,
> +	.disable = pwm_lpss_disable,
> +	.owner = THIS_MODULE,
> +};
> +
> +static int pwm_lpss_probe(struct platform_device *pdev)
> +{
> +	struct pwm_lpss_chip *lpwm;
> +	struct resource *r;
> +	int ret;
> +
> +	lpwm = devm_kzalloc(&pdev->dev, sizeof(*lpwm), GFP_KERNEL);
> +	if (!lpwm)
> +		return -ENOMEM;
> +
> +	lpwm->chip.dev = &pdev->dev;
> +	lpwm->chip.ops = &pwm_lpss_ops;
> +	lpwm->chip.base = -1;
> +	lpwm->chip.npwm = 1;
> +
> +	lpwm->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(lpwm->clk)) {
> +		dev_err(&pdev->dev, "failed to get pwm clk\n");
> +		return -ENODEV;
> +	}
> +
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!r) {
> +		dev_err(&pdev->dev, "failed to get mmio base\n");
> +		return -ENODEV;
> +	}
> +
> +	lpwm->regs = devm_request_and_ioremap(lpwm->chip.dev, r);
> +	if (!lpwm->regs)
> +		return -EBUSY;
> +
> +	ret = pwmchip_add(&lpwm->chip);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
> +		return ret;
> +	}
> +
> +	platform_set_drvdata(pdev, lpwm);
> +	return 0;
> +}
> +
> +static int pwm_lpss_remove(struct platform_device *pdev)
> +{
> +	struct pwm_lpss_chip *lpwm = platform_get_drvdata(pdev);
> +
> +	pwm_lpss_set_state(lpwm, false);
> +	return pwmchip_remove(&lpwm->chip);
> +}
> +
> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id pwm_lpss_acpi_match[] = {
> +	{ "80860F08", 0 },
> +	{ "80860F09", 0 },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match);
> +#endif
> +
> +static struct platform_driver pwm_lpss_driver = {
> +	.driver = {
> +		.name = "pwm-lpss",
> +		.acpi_match_table = ACPI_PTR(pwm_lpss_acpi_match),
> +	},
> +	.probe = pwm_lpss_probe,
> +	.remove = pwm_lpss_remove,
> +};
> +module_platform_driver(pwm_lpss_driver);
> +
> +MODULE_DESCRIPTION("PWM driver for Intel LPSS");
> +MODULE_AUTHOR("Mika Westerberg <mika.westerberg at linux.intel.com>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:pwm-lpss");