pwm: add support for Intel Low Power Subsystem PWM

Add support for Intel Low Power I/O subsystem PWM controllers found on
Intel BayTrail SoC.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Chew, Kean Ho <kean.ho.chew@intel.com>
Signed-off-by: Chang, Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
Signed-off-by: Chew, Chiau Ee <chiau.ee.chew@intel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
(cherry picked from commit d16a5aa9e821633a3095d7a88cd1d2cd108bf966)

Signed-off-by: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 22f2f28..36bf194 100644 (file)
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -119,6 +119,16 @@ 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-lpss.
+
 config PWM_MXS
        tristate "Freescale MXS PWM support"
        depends on ARCH_MXS && OF

diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index d8906ec..61bf073 100644 (file)
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_PWM_IMX)           += pwm-imx.o
 obj-$(CONFIG_PWM_JZ4740)       += pwm-jz4740.o
 obj-$(CONFIG_PWM_LP3943)       += pwm-lp3943.o
 obj-$(CONFIG_PWM_LPC32XX)      += pwm-lpc32xx.o
+obj-$(CONFIG_PWM_LPSS)         += pwm-lpss.o
 obj-$(CONFIG_PWM_MXS)          += pwm-mxs.o
 obj-$(CONFIG_PWM_PCA9685)      += pwm-pca9685.o
 obj-$(CONFIG_PWM_PUV3)         += pwm-puv3.o

diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
new file mode 100644 (file)
index 0000000..449e372
--- /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");