pwm: crc: Add Crystalcove (CRC) PWM driver

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@linux.intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Reviewed-by: Varka Bhadram <varkabhadram@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

3 files changed, 151 insertions, 0 deletions

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index b1541f40fd8d..948d9abd27f1 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 ec50eb5b5a8f..d186f35a6538 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 000000000000..7101c7020bf4
--- /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@intel.com>
+ */
+
+#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);