pwm: Add support for the Berlin PWM controller

Add a PWM controller driver for the Marvell Berlin SoCs. This PWM
controller has 4 channels.
Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/Kconfig

@@ -92,6 +92,15 @@ config PWM_BCM2835
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-bcm2835.
 
+config PWM_BERLIN
+	tristate "Marvell Berlin PWM support"
+	depends on ARCH_BERLIN
+	help
+	  PWM framework driver for Marvell Berlin SoCs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-berlin.
+
 config PWM_BFIN
 	tristate "Blackfin PWM support"
 	depends on BFIN_GPTIMERS

drivers/pwm/Makefile

@@ -6,6 +6,7 @@ obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM)	+= pwm-atmel-hlcdc.o
 obj-$(CONFIG_PWM_ATMEL_TCB)	+= pwm-atmel-tcb.o
 obj-$(CONFIG_PWM_BCM_KONA)	+= pwm-bcm-kona.o
 obj-$(CONFIG_PWM_BCM2835)	+= pwm-bcm2835.o
+obj-$(CONFIG_PWM_BERLIN)	+= pwm-berlin.o
 obj-$(CONFIG_PWM_BFIN)		+= pwm-bfin.o
 obj-$(CONFIG_PWM_CLPS711X)	+= pwm-clps711x.o
 obj-$(CONFIG_PWM_CRC)		+= pwm-crc.o

drivers/pwm/pwm-berlin.c

+/*
+ * Marvell Berlin PWM driver
+ *
+ * Copyright (C) 2015 Marvell Technology Group Ltd.
+ *
+ * Author: Antoine Tenart <antoine.tenart@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#define BERLIN_PWM_EN			0x0
+#define  BERLIN_PWM_ENABLE		BIT(0)
+#define BERLIN_PWM_CONTROL		0x4
+#define  BERLIN_PWM_PRESCALE_MASK	0x7
+#define  BERLIN_PWM_PRESCALE_MAX	4096
+#define  BERLIN_PWM_INVERT_POLARITY	BIT(3)
+#define BERLIN_PWM_DUTY			0x8
+#define BERLIN_PWM_TCNT			0xc
+#define  BERLIN_PWM_MAX_TCNT		65535
+
+struct berlin_pwm_chip {
+	struct pwm_chip chip;
+	struct clk *clk;
+	void __iomem *base;
+};
+
+static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct berlin_pwm_chip, chip);
+}
+
+static const u32 prescaler_table[] = {
+	1, 4, 8, 16, 64, 256, 1024, 4096
+};
+
+static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *chip,
+				   unsigned int channel, unsigned long offset)
+{
+	return readl_relaxed(chip->base + channel * 0x10 + offset);
+}
+
+static inline void berlin_pwm_writel(struct berlin_pwm_chip *chip,
+				     unsigned int channel, u32 value,
+				     unsigned long offset)
+{
+	writel_relaxed(value, chip->base + channel * 0x10 + offset);
+}
+
+static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev,
+			     int duty_ns, int period_ns)
+{
+	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
+	unsigned int prescale;
+	u32 value, duty, period;
+	u64 cycles, tmp;
+
+	cycles = clk_get_rate(pwm->clk);
+	cycles *= period_ns;
+	do_div(cycles, NSEC_PER_SEC);
+
+	for (prescale = 0; prescale < ARRAY_SIZE(prescaler_table); prescale++) {
+		tmp = cycles;
+		do_div(tmp, prescaler_table[prescale]);
+
+		if (tmp <= BERLIN_PWM_MAX_TCNT)
+			break;
+	}
+
+	if (tmp > BERLIN_PWM_MAX_TCNT)
+		return -ERANGE;
+
+	period = tmp;
+	cycles = tmp * duty_ns;
+	do_div(cycles, period_ns);
+	duty = cycles;
+
+	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
+	value &= ~BERLIN_PWM_PRESCALE_MASK;
+	value |= prescale;
+	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
+
+	berlin_pwm_writel(pwm, pwm_dev->hwpwm, duty, BERLIN_PWM_DUTY);
+	berlin_pwm_writel(pwm, pwm_dev->hwpwm, period, BERLIN_PWM_TCNT);
+
+	return 0;
+}
+
+static int berlin_pwm_set_polarity(struct pwm_chip *chip,
+				   struct pwm_device *pwm_dev,
+				   enum pwm_polarity polarity)
+{
+	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
+	u32 value;
+
+	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
+
+	if (polarity == PWM_POLARITY_NORMAL)
+		value &= ~BERLIN_PWM_INVERT_POLARITY;
+	else
+		value |= BERLIN_PWM_INVERT_POLARITY;
+
+	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
+
+	return 0;
+}
+
+static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm_dev)
+{
+	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
+	u32 value;
+
+	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
+	value |= BERLIN_PWM_ENABLE;
+	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
+
+	return 0;
+}
+
+static void berlin_pwm_disable(struct pwm_chip *chip,
+			       struct pwm_device *pwm_dev)
+{
+	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
+	u32 value;
+
+	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
+	value &= ~BERLIN_PWM_ENABLE;
+	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
+}
+
+static const struct pwm_ops berlin_pwm_ops = {
+	.config = berlin_pwm_config,
+	.set_polarity = berlin_pwm_set_polarity,
+	.enable = berlin_pwm_enable,
+	.disable = berlin_pwm_disable,
+	.owner = THIS_MODULE,
+};
+
+static const struct of_device_id berlin_pwm_match[] = {
+	{ .compatible = "marvell,berlin-pwm" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, berlin_pwm_match);
+
+static int berlin_pwm_probe(struct platform_device *pdev)
+{
+	struct berlin_pwm_chip *pwm;
+	struct resource *res;
+	int ret;
+
+	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+	if (!pwm)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	pwm->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(pwm->base))
+		return PTR_ERR(pwm->base);
+
+	pwm->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(pwm->clk))
+		return PTR_ERR(pwm->clk);
+
+	ret = clk_prepare_enable(pwm->clk);
+	if (ret)
+		return ret;
+
+	pwm->chip.dev = &pdev->dev;
+	pwm->chip.ops = &berlin_pwm_ops;
+	pwm->chip.base = -1;
+	pwm->chip.npwm = 4;
+	pwm->chip.can_sleep = true;
+	pwm->chip.of_xlate = of_pwm_xlate_with_flags;
+	pwm->chip.of_pwm_n_cells = 3;
+
+	ret = pwmchip_add(&pwm->chip);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
+		clk_disable_unprepare(pwm->clk);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, pwm);
+
+	return 0;
+}
+
+static int berlin_pwm_remove(struct platform_device *pdev)
+{
+	struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev);
+	int ret;
+
+	ret = pwmchip_remove(&pwm->chip);
+	clk_disable_unprepare(pwm->clk);
+
+	return ret;
+}
+
+static struct platform_driver berlin_pwm_driver = {
+	.probe = berlin_pwm_probe,
+	.remove = berlin_pwm_remove,
+	.driver = {
+		.name = "berlin-pwm",
+		.of_match_table = berlin_pwm_match,
+	},
+};
+module_platform_driver(berlin_pwm_driver);
+
+MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
+MODULE_DESCRIPTION("Marvell Berlin PWM driver");
+MODULE_LICENSE("GPL v2");