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Subject[PATCH v2] pwm: add support for Intel Low Power Subsystem PWM
Date
From: Mika Westerberg <mika.westerberg@linux.intel.com>

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>
---
drivers/pwm/Kconfig | 10 +++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-lpss.c | 179 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 190 insertions(+), 0 deletions(-)
create mode 100644 drivers/pwm/pwm-lpss.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 0b7a3c9..aaa91cc 100644
--- 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
--- 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
index 0000000..2ecd945
--- /dev/null
+++ b/drivers/pwm/pwm-lpss.c
@@ -0,0 +1,179 @@
+/*
+ * 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 = clk_get_rate(lpwm->clk);
+ 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;
+ 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[] = {
+ { "80860F08", 0 },
+ { "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("GPLv2");
+MODULE_ALIAS("platform:pwm-lpss");
--
1.7.4.4


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