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authorMika Westerberg <mika.westerberg@linux.intel.com>2014-03-20 22:04:23 +0800
committerThierry Reding <thierry.reding@gmail.com>2014-04-01 12:03:40 +0200
commitd16a5aa9e821633a3095d7a88cd1d2cd108bf966 (patch)
tree0e0a627503aea9fe3c3075ae79046777d2778619 /drivers/pwm/pwm-lpss.c
parent7eb3f6ffb5c3635e8cc5df7b19741b4bfc5894f5 (diff)
downloadlinux-stericsson-d16a5aa9e821633a3095d7a88cd1d2cd108bf966.tar.gz
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>
Diffstat (limited to 'drivers/pwm/pwm-lpss.c')
-rw-r--r--drivers/pwm/pwm-lpss.c183
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");