[RFC v6 6/8] drivers/pwm: Add Crystalcove (CRC) PWM driver

Shobhit Kumar
2015-04-24T15:33:40Z

The Crystalcove PMIC controls PWM signals and this driver exports that
capability as a PWM chip driver. This is platform device implementtaion
of the drivers/mfd cell device for CRC PMIC

v2: Use the existing config callback with duty_ns and period_ns(Thierry)

CC: Samuel Ortiz <sameo@linux.intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
---
drivers/pwm/Kconfig | 7 +++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-crc.c | 171 ++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 179 insertions(+)
create mode 100644 drivers/pwm/pwm-crc.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index b1541f4..954da3e 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -183,6 +183,13 @@ config PWM_LPC32XX
To compile this driver as a module, choose M here: the module
will be called pwm-lpc32xx.

+config PWM_CRC
+ bool "Intel Crystalcove (CRC) PWM support"
+ depends on X86 && INTEL_SOC_PMIC
+ help
+ Generic PWM framework driver for Crystalcove (CRC) PMIC based PWM
+ control.
+
config PWM_LPSS
tristate "Intel LPSS PWM support"
depends on X86
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index ec50eb5..3d38fed 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -35,3 +35,4 @@ obj-$(CONFIG_PWM_TIPWMSS) += pwm-tipwmss.o
obj-$(CONFIG_PWM_TWL) += pwm-twl.o
obj-$(CONFIG_PWM_TWL_LED) += pwm-twl-led.o
obj-$(CONFIG_PWM_VT8500) += pwm-vt8500.o
+obj-$(CONFIG_PWM_CRC) += pwm-crc.o
diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c
new file mode 100644
index 0000000..987f3b4
--- /dev/null
+++ b/drivers/pwm/pwm-crc.c
@@ -0,0 +1,171 @@
+/*
+ * pwm-crc.c - Intel Crystal Cove PWM Driver
+ *
+ * Copyright (C) 2015 Intel Corporation. All rights reserved.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * Author: Shobhit Kumar <shobhit.kumar@intel.com>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/mfd/intel_soc_pmic.h>
+#include <linux/pwm.h>
+
+#define PWM0_CLK_DIV 0x4B
+#define PWM_OUTPUT_ENABLE (1<<7)
+#define PWM_DIV_CLK_0 0x00 /* DIVIDECLK = BASECLK */
+#define PWM_DIV_CLK_100 0x63 /* DIVIDECLK = BASECLK/100 */
+#define PWM_DIV_CLK_128 0x7F /* DIVIDECLK = BASECLK/128 */
+
+#define PWM0_DUTY_CYCLE 0x4E
+#define BACKLIGHT_EN 0x51
+
+#define PWM_MAX_LEVEL 0xFF
+
+#define PWM_BASE_CLK 6000 /* 6 MHz */
+#define PWM_MAX_PERIOD_NS 21333 /* 46.875KHz */
+
+/**
+ * struct crystalcove_pwm - Crystal Cove PWM controller
+ * @chip: the abstract pwm_chip structure.
+ * @regmap: the regmap from the parent device.
+ */
+struct crystalcove_pwm {
+ struct pwm_chip chip;
+ struct platform_device *pdev;
+ struct regmap *regmap;
+};
+
+static inline struct crystalcove_pwm *to_crc_pwm(struct pwm_chip *pc)
+{
+ return container_of(pc, struct crystalcove_pwm, chip);
+}
+
+static int crc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
+{
+ struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
+
+ regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 1);
+
+ return 0;
+}
+
+static void crc_pwm_disable(struct pwm_chip *c, struct pwm_device *pwm)
+{
+ struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
+
+ regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 0);
+}
+
+static int crc_pwm_config(struct pwm_chip *c, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
+ struct device *dev = &crc_pwm->pdev->dev;
+ int level, percent;
+
+ if (period_ns > PWM_MAX_PERIOD_NS) {
+ dev_err(dev, "un-supported period_ns\n");
+ return -1;
+ }
+
+ if (pwm->period != period_ns) {
+ int clk_div;
+
+ /* changing the clk divisor, need to disable fisrt */
+ crc_pwm_disable(c, pwm);
+ clk_div = PWM_BASE_CLK * period_ns / 1000000;
+
+ regmap_write(crc_pwm->regmap, PWM0_CLK_DIV,
+ clk_div | PWM_OUTPUT_ENABLE);
+
+ /* enable back */
+ crc_pwm_enable(c, pwm);
+ }
+
+ if (duty_ns > period_ns) {
+ dev_err(dev, "duty cycle cannot be greater than cycle period\n");
+ return -1;
+ }
+
+ /* change the pwm duty cycle */
+ percent = duty_ns * 100 / period_ns;
+ level = percent * PWM_MAX_LEVEL / 100;
+ regmap_write(crc_pwm->regmap, PWM0_DUTY_CYCLE, level);
+
+ return 0;
+}
+
+static const struct pwm_ops crc_pwm_ops = {
+ .config = crc_pwm_config,
+ .enable = crc_pwm_enable,
+ .disable = crc_pwm_disable,
+ .owner = THIS_MODULE,
+};
+
+static int crystalcove_pwm_probe(struct platform_device *pdev)
+{
+ struct crystalcove_pwm *pwm;
+ int retval;
+ struct device *dev = pdev->dev.parent;
+ struct intel_soc_pmic *pmic = dev_get_drvdata(dev);
+
+ pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+ if (!pwm)
+ return -ENOMEM;
+
+ pwm->chip.dev = &pdev->dev;
+ pwm->chip.ops = &crc_pwm_ops;
+ pwm->chip.base = -1;
+ pwm->chip.npwm = 1;
+
+ /* get the PMIC regmap */
+ pwm->regmap = pmic->regmap;
+
+ retval = pwmchip_add(&pwm->chip);
+ if (retval < 0)
+ return retval;
+
+ dev_dbg(&pdev->dev, "crc-pwm probe successful\n");
+ platform_set_drvdata(pdev, pwm);
+
+ return 0;
+}
+
+static int crystalcove_pwm_remove(struct platform_device *pdev)
+{
+ struct crystalcove_pwm *pwm = platform_get_drvdata(pdev);
+ int retval;
+
+ retval = pwmchip_remove(&pwm->chip);
+ if (retval < 0)
+ return retval;
+
+ dev_dbg(&pdev->dev, "crc-pwm driver removed\n");
+
+ return 0;
+}
+
+static struct platform_driver crystalcove_pwm_driver = {
+ .probe = crystalcove_pwm_probe,
+ .remove = crystalcove_pwm_remove,
+ .driver = {
+ .name = "crystal_cove_pwm",
+ },
+};
+
+module_platform_driver(crystalcove_pwm_driver);
+
+MODULE_AUTHOR("Shobhit Kumar <shobhit.kumar@intel.com>");
+MODULE_DESCRIPTION("Intel Crystal Cove PWM Driver");
+MODULE_LICENSE("GPL v2");