[PATCH v2] pwm: Add MC34708 PWM driver support.

[Denis Carikli <denis@eukrea.com>]

Signed-off-by: Denis Carikli <denis@eukrea.com>
---
Changelog v1->v2:

- The driver now uses retrives mc13xxx without having to export it
  trough a globally exported function.
- The .enable() and .disable() are now handled.
- The registers calculations have been reworked.
- Defines have been reworked to be more readable.
- The driver only supports the mc34708, so now we don't claim to support
  other devices anymore, and the prefix has been changed from mc13xxx
  to mc34708. The documentation was also updated to reflect that.
- Spelling errors have been fixed.
- There is now less code thanks to the use of mc13xxx_reg_rmw and
  range checking functions.
- Many other cosmetics fixes and code cleanups.
---
 Documentation/devicetree/bindings/mfd/mc13xxx.txt |    3 +
 drivers/mfd/mc13xxx-core.c                        |   16 ++
 drivers/pwm/Kconfig                               |    6 +
 drivers/pwm/Makefile                              |    1 +
 drivers/pwm/pwm-mc34708.c                         |  224 +++++++++++++++++++++
 5 files changed, 250 insertions(+)
 create mode 100644 drivers/pwm/pwm-mc34708.c

diff --git a/Documentation/devicetree/bindings/mfd/mc13xxx.txt b/Documentation/devicetree/bindings/mfd/mc13xxx.txt
index 8aba488..464a663 100644
--- a/Documentation/devicetree/bindings/mfd/mc13xxx.txt
+++ b/Documentation/devicetree/bindings/mfd/mc13xxx.txt
@@ -22,6 +22,9 @@ Sub-nodes:
   Each led node should contain "reg", which used as LED ID (described below).
   Optional properties "label" and "linux,default-trigger" is described in
   Documentation/devicetree/bindings/leds/common.txt.
+- pwm: For MC34708, contain the PWM controller:
+  - compatible: must be "fsl,mc34708-pwm".
+  - #pwm-cells: must be 2.
 - regulators : Contain the regulator nodes. The regulators are bound using
   their names as listed below with their registers and bits for enabling.
 
diff --git a/drivers/mfd/mc13xxx-core.c b/drivers/mfd/mc13xxx-core.c
index acf5dd7..71b7d84c 100644
--- a/drivers/mfd/mc13xxx-core.c
+++ b/drivers/mfd/mc13xxx-core.c
@@ -599,6 +599,20 @@ static int mc13xxx_add_subdevice_pdata(struct mc13xxx *mc13xxx,
 	if (!cell.name)
 		return -ENOMEM;
 
+	/* mfd_add_devices won't adds a .of_node to the child's dev if the
+	 * cell's .off_compatible is NULL, which result in
+	 * of_node_to_pwmchip beeing unable to find the pwm device.
+	 */
+	if (!strncmp(format, "%s-pwm", sizeof("%s-pwm"))) {
+		if (snprintf(buf, sizeof(buf),
+			     "fsl,%s", cell.name) > sizeof(buf))
+			return -E2BIG;
+
+		cell.of_compatible = kmemdup(buf, strlen(buf) + 1, GFP_KERNEL);
+		if (!cell.of_compatible)
+			return -ENOMEM;
+	}
+
 	return mfd_add_devices(mc13xxx->dev, -1, &cell, 1, NULL, 0, NULL);
 }
 
@@ -681,6 +695,7 @@ int mc13xxx_common_init(struct device *dev)
 			&pdata->regulators, sizeof(pdata->regulators));
 		mc13xxx_add_subdevice_pdata(mc13xxx, "%s-led",
 				pdata->leds, sizeof(*pdata->leds));
+		mc13xxx_add_subdevice(mc13xxx, "%s-pwm");
 		mc13xxx_add_subdevice_pdata(mc13xxx, "%s-pwrbutton",
 				pdata->buttons, sizeof(*pdata->buttons));
 		if (mc13xxx->flags & MC13XXX_USE_CODEC)
@@ -692,6 +707,7 @@ int mc13xxx_common_init(struct device *dev)
 	} else {
 		mc13xxx_add_subdevice(mc13xxx, "%s-regulator");
 		mc13xxx_add_subdevice(mc13xxx, "%s-led");
+		mc13xxx_add_subdevice(mc13xxx, "%s-pwm");
 		mc13xxx_add_subdevice(mc13xxx, "%s-pwrbutton");
 		if (mc13xxx->flags & MC13XXX_USE_CODEC)
 			mc13xxx_add_subdevice(mc13xxx, "%s-codec");
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 4ad7b89..a7ca3eb 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -157,6 +157,12 @@ config PWM_LPSS
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-lpss.
 
+config PWM_MC34708
+	tristate "MC34708 PWM support"
+	depends on MFD_MC13XXX
+	help
+	  Generic PWM framework driver for Freescale MC34708 PMIC.
+
 config PWM_MXS
 	tristate "Freescale MXS PWM support"
 	depends on ARCH_MXS && OF
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 5c86a19..0fe5ec5 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -13,6 +13,7 @@ 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-$(CONFIG_PWM_MC34708)	+= pwm-mc34708.o
 obj-$(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-mc34708.c b/drivers/pwm/pwm-mc34708.c
new file mode 100644
index 0000000..840f4dc
--- /dev/null
+++ b/drivers/pwm/pwm-mc34708.c
@@ -0,0 +1,224 @@
+/*
+ * Copyright 2014 Eukréa Electromatique <denis@eukrea.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * 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.
+ */
+
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#include <linux/mfd/mc13783.h>
+
+/* PWM register address */
+#define MC134708_PWM		0x37
+
+/* PWM register fields:
+ * Bit #    RegisterName Description
+ *  [0->5]  PWM1DUTY:   PWM1 duty cycle
+ *  [6->11] PWM1CLKDIV: PWM1 duty cycle
+ * [12->17] PWM2DUTY:   PWM2 clock divide setting
+ * [18->23] PWM2CLKDIV: PWM2 clock divide setting
+ */
+#define MC134708_PWM_MASK			0x3f
+#define MC134708_PWM_NUM_OFFSET			0x0c
+
+#define MC134708_PWM_DUTY_OFFSET(pwm_id)	(pwm_id * MC134708_PWM_NUM_OFFSET)
+#define MC134708_PWM_PERIOD_OFFSET(pwm_id)	((pwm_id * MC134708_PWM_NUM_OFFSET) + 0x06)
+
+/* MC34708 PWM Constraints */
+#define MC13708_BASE_CLK_FREQ	2000000
+#define MC13708_PWM_MAX_DUTY	32
+#define MC13708_PWM_MAX_CLKDIV	64
+
+#define MC13708_MIN_PWM_PERIOD	(NSEC_PER_SEC / MC13708_BASE_CLK_FREQ)
+#define MC13708_MAX_PWM_PERIOD	(MC13708_MIN_PWM_PERIOD * MC13708_PWM_MAX_CLKDIV)
+
+#define MC134708_PWMS_NUM	2
+
+struct mc34708_pwm_regs {
+	int enabled;
+	int pwm_duty;
+};
+
+struct mc34708_pwm_chip {
+	struct pwm_chip pwm_chip;
+	struct mc13xxx *mc13xxx;
+	struct mc34708_pwm_regs *pwms[MC134708_PWMS_NUM];
+};
+
+static inline
+struct mc34708_pwm_chip *to_mc34708_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct mc34708_pwm_chip, pwm_chip);
+}
+
+static int
+pwm_mc34708_config(struct pwm_chip *chip, struct pwm_device *pwm,
+			      int duty_ns, int period_ns)
+{
+	struct mc34708_pwm_chip *mc34708_chip = to_mc34708_chip(chip);
+	struct mc34708_pwm_regs *pwmr = mc34708_chip->pwms[pwm->hwpwm];
+	struct mc13xxx *mc13xxx = mc34708_chip->mc13xxx;
+
+	int duty_offset = MC134708_PWM_DUTY_OFFSET(pwm->hwpwm);
+	int period_offset = MC134708_PWM_PERIOD_OFFSET(pwm->hwpwm);
+
+	int pwm_clkdiv, pwm_duty, ret = 0;
+
+	/* Period */
+	period_ns = clamp(period_ns, (int)MC13708_MIN_PWM_PERIOD,
+			  (int)MC13708_MAX_PWM_PERIOD);
+	pwm_clkdiv = DIV_ROUND_UP(NSEC_PER_SEC, period_ns); /* Frequency (Hz) */
+	pwm_clkdiv = DIV_ROUND_UP(MC13708_BASE_CLK_FREQ,
+				  pwm_clkdiv) - 1; /* Clock divisor */
+
+	/* Duty cycle */
+	pwm_duty = DIV_ROUND_UP(MC13708_PWM_MAX_DUTY * duty_ns, period_ns);
+
+	/* Actual write to the registers */
+	mc13xxx_lock(mc13xxx);
+
+	ret = mc13xxx_reg_rmw(mc13xxx, MC134708_PWM,
+					MC134708_PWM_MASK << period_offset,
+					pwm_clkdiv << period_offset);
+	if (ret) {
+		mc13xxx_unlock(mc13xxx);
+		return ret;
+	}
+
+	/* The MC34708 doesn't have an enable bit for its PWM unit,
+	 * so we cache the pwm duty value for the .enable()
+	 */
+	pwmr->pwm_duty = pwm_duty;
+
+	if (pwmr->enabled) {
+		ret = mc13xxx_reg_rmw(mc13xxx, MC134708_PWM,
+				MC134708_PWM_MASK << duty_offset,
+				pwm_duty << duty_offset);
+	}
+	mc13xxx_unlock(mc13xxx);
+
+	return ret;
+}
+
+static int pwm_mc34708_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct mc34708_pwm_chip *mc34708_chip = to_mc34708_chip(chip);
+	struct mc34708_pwm_regs *pwmr = mc34708_chip->pwms[pwm->hwpwm];
+	struct mc13xxx *mc13xxx = mc34708_chip->mc13xxx;
+	int duty_offset = MC134708_PWM_DUTY_OFFSET(pwm->hwpwm);
+	int ret;
+
+	mc13xxx_lock(mc13xxx);
+
+	ret = mc13xxx_reg_rmw(mc13xxx, MC134708_PWM,
+			MC134708_PWM_MASK << duty_offset,
+			pwmr->pwm_duty << duty_offset);
+	pwmr->enabled = 1;
+
+	mc13xxx_unlock(mc13xxx);
+
+	return ret;
+}
+
+static void pwm_mc34708_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct mc34708_pwm_chip *mc34708_chip = to_mc34708_chip(chip);
+	struct mc34708_pwm_regs *pwmr = mc34708_chip->pwms[pwm->hwpwm];
+	struct mc13xxx *mc13xxx = mc34708_chip->mc13xxx;
+	int duty_offset = MC134708_PWM_DUTY_OFFSET(pwm->hwpwm);
+
+	mc13xxx_lock(mc13xxx);
+
+	/* To disable the PWM, the duty cycle bits have to be cleared */
+	mc13xxx_reg_rmw(mc13xxx, MC134708_PWM,
+			MC134708_PWM_MASK << duty_offset,
+			0 << duty_offset);
+	pwmr->enabled = 0;
+
+	mc13xxx_unlock(mc13xxx);
+}
+
+static const struct pwm_ops pwm_mc34708_ops = {
+	.enable		= pwm_mc34708_enable,
+	.disable	= pwm_mc34708_disable,
+	.config		= pwm_mc34708_config,
+	.owner		= THIS_MODULE,
+};
+
+static int pwm_mc34708_probe(struct platform_device *pdev)
+{
+	struct mc34708_pwm_chip *chip;
+	struct mc13xxx *mc13xxx;
+	int err, i;
+
+	mc13xxx = dev_get_drvdata(pdev->dev.parent);
+
+	if (!mc13xxx)
+		return -EINVAL;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+			return -ENOMEM;
+
+	for (i = 0; i < MC134708_PWMS_NUM; i++) {
+		chip->pwms[i] = devm_kzalloc(&pdev->dev,
+			sizeof(struct mc34708_pwm_regs), GFP_KERNEL);
+	}
+
+	chip->mc13xxx = mc13xxx;
+	chip->pwm_chip.dev = &pdev->dev;
+	chip->pwm_chip.ops = &pwm_mc34708_ops;
+	chip->pwm_chip.base = -1;
+	chip->pwm_chip.npwm = MC134708_PWMS_NUM;
+
+	err = pwmchip_add(&chip->pwm_chip);
+	if (err < 0)
+		return err;
+
+	platform_set_drvdata(pdev, chip);
+
+	return 0;
+}
+
+static int pwm_mc34708_remove(struct platform_device *pdev)
+{
+	struct mc34708_pwm_chip *chip = platform_get_drvdata(pdev);
+
+	return pwmchip_remove(&chip->pwm_chip);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id pwm_mc34708_of_match[] = {
+	{ .compatible = "fsl,mc34708-pwm" },
+	{ /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pwm_mc34708_of_match);
+#endif
+
+static struct platform_driver pwm_mc34708_driver = {
+	.driver	= {
+		.name = "mc34708-pwm",
+		.of_match_table = of_match_ptr(pwm_mc34708_of_match),
+	},
+	.probe = pwm_mc34708_probe,
+	.remove = pwm_mc34708_remove,
+};
+module_platform_driver(pwm_mc34708_driver);
+
+MODULE_ALIAS("platform:mc34708-pwm");
+MODULE_AUTHOR("Denis Carikli <denis@eukrea.com>");
+MODULE_DESCRIPTION("mc34708 Pulse Width Modulation Driver");
+MODULE_LICENSE("GPL");
-- 
1.7.9.5