diff options
Diffstat (limited to 'drivers/pwm/pwm-lpss.c')
| -rw-r--r-- | drivers/pwm/pwm-lpss.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c new file mode 100644 index 000000000000..449e372050a0 --- /dev/null +++ b/drivers/pwm/pwm-lpss.c @@ -0,0 +1,183 @@ +/* + * Intel Low Power Subsystem PWM controller driver + * + * Copyright (C) 2014, Intel Corporation + * Author: Mika Westerberg <mika.westerberg@linux.intel.com> + * Author: Chew Kean Ho <kean.ho.chew@intel.com> + * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com> + * Author: Chew Chiau Ee <chiau.ee.chew@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 +#define PWM_DIVISION_CORRECTION 0x2 +#define PWM_LIMIT (0x8000 + PWM_DIVISION_CORRECTION) +#define NSECS_PER_SEC 1000000000UL + +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 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 on_time_div; + unsigned long c; + unsigned long long base_unit, freq = NSECS_PER_SEC; + u32 ctrl; + + do_div(freq, period_ns); + + /* The equation is: base_unit = ((freq / c) * 65536) + correction */ + base_unit = freq * 65536; + + c = clk_get_rate(lpwm->clk); + if (!c) + return -EINVAL; + + do_div(base_unit, c); + base_unit += PWM_DIVISION_CORRECTION; + if (base_unit > PWM_LIMIT) + return -EINVAL; + + if (duty_ns <= 0) + duty_ns = 1; + on_time_div = 255 - (255 * duty_ns / period_ns); + + ctrl = readl(lpwm->regs + PWM); + ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK); + ctrl |= (u16) base_unit << 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); + u32 ctrl; + int ret; + + ret = clk_prepare_enable(lpwm->clk); + if (ret) + return ret; + + ctrl = readl(lpwm->regs + PWM); + writel(ctrl | PWM_ENABLE, lpwm->regs + PWM); + + return 0; +} + +static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct pwm_lpss_chip *lpwm = to_lpwm(chip); + u32 ctrl; + + ctrl = readl(lpwm->regs + PWM); + writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM); + + 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 const struct acpi_device_id pwm_lpss_acpi_match[] = { + { "80860F09", 0 }, + { }, +}; +MODULE_DEVICE_TABLE(acpi, pwm_lpss_acpi_match); + +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; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + + lpwm->regs = devm_ioremap_resource(&pdev->dev, r); + if (IS_ERR(lpwm->regs)) + return PTR_ERR(lpwm->regs); + + lpwm->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(lpwm->clk)) { + dev_err(&pdev->dev, "failed to get PWM clock\n"); + return PTR_ERR(lpwm->clk); + } + + lpwm->chip.dev = &pdev->dev; + lpwm->chip.ops = &pwm_lpss_ops; + lpwm->chip.base = -1; + lpwm->chip.npwm = 1; + + 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); + u32 ctrl; + + ctrl = readl(lpwm->regs + PWM); + writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM); + + return pwmchip_remove(&lpwm->chip); +} + +static struct platform_driver pwm_lpss_driver = { + .driver = { + .name = "pwm-lpss", + .acpi_match_table = 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@linux.intel.com>"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:pwm-lpss"); |