[v3 5/7] pwm: crc: Add Crystalcove (CRC) PWM driver

[Shobhit Kumar <shobhit.kumar@xxxxxxxxx>]

The Crystalcove PMIC provides three PWM signals and this driver exports
one of them on the BYT platform which is used to control backlight for
DSI panel. This is platform device implementation of the drivers/mfd
cell device for CRC PMIC.

CC: Samuel Ortiz <sameo@xxxxxxxxxxxxxxx>
Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
Cc: Alexandre Courbot <gnurou@xxxxxxxxx>
Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
Cc: Paul Bolle <pebolle@xxxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Tested-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Shobhit Kumar <shobhit.kumar@xxxxxxxxx>
---
v2: Use the existing config callback with duty_ns and period_ns(Thierry)

v3: Correct the subject line (Lee jones)

v4: Address comment by Thierry & Paul
    - Commit message update and fixes for few syntax errors
    - Add PWM_CRC in Kconfig and Makefile sorted alphabetically
    - Use the PWM_BASE_CLK as 6000000 for better code readability
    - Remove the redundant rule of three while calculating pwm level
    - Use the platform_device in pwm_chip
    - Use builin_platform_driver

v5: Address comments by Varka
    - Make the bit definition using BIT macro
    - reorder probe and remove code to directly return from pwmchip_add/remove

 drivers/pwm/Kconfig   |   7 +++
 drivers/pwm/Makefile  |   1 +
 drivers/pwm/pwm-crc.c | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 151 insertions(+)
 create mode 100644 drivers/pwm/pwm-crc.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index b1541f4..948d9ab 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -111,6 +111,13 @@ config PWM_CLPS711X
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-clps711x.
 
+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_EP93XX
 	tristate "Cirrus Logic EP93xx PWM support"
 	depends on ARCH_EP93XX
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index ec50eb5..d186f35 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA)	+= pwm-bcm-kona.o
 obj-$(CONFIG_PWM_BCM2835)	+= pwm-bcm2835.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_CLPS711X)	+= pwm-clps711x.o
+obj-$(CONFIG_PWM_CRC)		+= pwm-crc.o
 obj-$(CONFIG_PWM_EP93XX)	+= pwm-ep93xx.o
 obj-$(CONFIG_PWM_FSL_FTM)	+= pwm-fsl-ftm.o
 obj-$(CONFIG_PWM_IMG)		+= pwm-img.o
diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c
new file mode 100644
index 0000000..7101c70
--- /dev/null
+++ b/drivers/pwm/pwm-crc.c
@@ -0,0 +1,143 @@
+/*
+ * 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@xxxxxxxxx>
+ */
+
+#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	BIT(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		6000000  /* 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 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->chip.dev;
+	int level;
+
+	if (period_ns > PWM_MAX_PERIOD_NS) {
+		dev_err(dev, "un-supported period_ns\n");
+		return -EINVAL;
+	}
+
+	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 / NSEC_PER_SEC;
+
+		regmap_write(crc_pwm->regmap, PWM0_CLK_DIV,
+					clk_div | PWM_OUTPUT_ENABLE);
+
+		/* enable back */
+		crc_pwm_enable(c, pwm);
+	}
+
+	/* change the pwm duty cycle */
+	level = duty_ns * PWM_MAX_LEVEL / period_ns;
+	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,
+};
+
+static int crystalcove_pwm_probe(struct platform_device *pdev)
+{
+	struct crystalcove_pwm *pwm;
+	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;
+
+	platform_set_drvdata(pdev, pwm);
+
+	return pwmchip_add(&pwm->chip);
+}
+
+static int crystalcove_pwm_remove(struct platform_device *pdev)
+{
+	struct crystalcove_pwm *pwm = platform_get_drvdata(pdev);
+
+	return pwmchip_remove(&pwm->chip);
+}
+
+static struct platform_driver crystalcove_pwm_driver = {
+	.probe = crystalcove_pwm_probe,
+	.remove = crystalcove_pwm_remove,
+	.driver = {
+		.name = "crystal_cove_pwm",
+	},
+};
+
+builtin_platform_driver(crystalcove_pwm_driver);
-- 
1.9.1

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