[PATCH 08/15] pwm: Add new pwm-samsung driver

Tomasz Figa tomasz.figa at gmail.com
Wed Jun 5 17:18:13 EDT 2013


This patch introduces new Samsung PWM driver, which uses Samsung
PWM/timer master driver to control shared parts of the hardware.

Signed-off-by: Tomasz Figa <tomasz.figa at gmail.com>
---
 drivers/pwm/Makefile      |   1 +
 drivers/pwm/pwm-samsung.c | 528 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 529 insertions(+)
 create mode 100644 drivers/pwm/pwm-samsung.c

diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 229a599..833c3ac 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_PWM_MXS)		+= pwm-mxs.o
 obj-$(CONFIG_PWM_PUV3)		+= pwm-puv3.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
 obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung-legacy.o
+obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
 obj-$(CONFIG_PWM_SPEAR)		+= pwm-spear.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o
 obj-$(CONFIG_PWM_TIECAP)	+= pwm-tiecap.o
diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c
new file mode 100644
index 0000000..61bed3d
--- /dev/null
+++ b/drivers/pwm/pwm-samsung.c
@@ -0,0 +1,528 @@
+/* drivers/pwm/pwm-samsung.c
+ *
+ * Copyright (c) 2007 Ben Dooks
+ * Copyright (c) 2008 Simtec Electronics
+ *     Ben Dooks <ben at simtec.co.uk>, <ben-linux at fluff.org>
+ * Copyright (c) 2013 Tomasz Figa <tomasz.figa at gmail.com>
+ *
+ * PWM driver for Samsung SoCs
+ *
+ * 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.
+*/
+
+#include <linux/clk.h>
+#include <linux/export.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/time.h>
+
+#include <clocksource/samsung_pwm.h>
+
+#define REG_TCFG0			0x00
+#define REG_TCFG1			0x04
+#define REG_TCON			0x08
+
+#define REG_TCNTB(tmr)			(0x0c + ((tmr) * 0xc))
+#define REG_TCMPB(tmr)			(0x10 + ((tmr) * 0xc))
+
+#define TCFG0_PRESCALER_MASK		0xff
+#define TCFG0_PRESCALER1_SHIFT		8
+
+#define TCFG1_MUX_MASK			0xf
+#define TCFG1_SHIFT(x)			((x) * 4)
+
+#define TCON_START(chan)		(1 << (4 * (chan) + 0))
+#define TCON_MANUALUPDATE(chan)		(1 << (4 * (chan) + 1))
+#define TCON_INVERT(chan)		(1 << (4 * (chan) + 2))
+#define TCON_AUTORELOAD(chan)		(1 << (4 * (chan) + 3))
+
+struct samsung_pwm_channel {
+	unsigned long period_ns;
+	unsigned long duty_ns;
+	unsigned long tin_ns;
+};
+
+struct samsung_pwm_chip {
+	struct pwm_chip chip;
+	struct samsung_pwm_variant variant;
+	struct samsung_pwm_channel channels[SAMSUNG_PWM_NUM];
+
+	void __iomem *base;
+	struct clk *base_clk;
+	struct clk *tclk0;
+	struct clk *tclk1;
+};
+#define to_samsung_pwm_chip(chip)	\
+			container_of(chip, struct samsung_pwm_chip, chip)
+
+#ifndef CONFIG_CLKSRC_SAMSUNG_PWM
+static DEFINE_SPINLOCK(samsung_pwm_lock);
+#endif
+
+static void pwm_samsung_set_divisor(struct samsung_pwm_chip *pwm,
+					unsigned int channel, u8 divisor)
+{
+	u8 shift = TCFG1_SHIFT(channel);
+	unsigned long flags;
+	u32 reg;
+	u8 bits;
+
+	bits = (fls(divisor) - 1) - pwm->variant.div_base;
+
+	spin_lock_irqsave(&samsung_pwm_lock, flags);
+
+	reg = readl(pwm->base + REG_TCFG1);
+	reg &= ~(TCFG1_MUX_MASK << shift);
+	reg |= bits << shift;
+	writel(reg, pwm->base + REG_TCFG1);
+
+	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
+}
+
+static inline int pwm_samsung_is_tdiv(struct samsung_pwm_chip *chip,
+							unsigned int chan)
+{
+	struct samsung_pwm_variant *variant = &chip->variant;
+	u32 reg;
+
+	reg = readl(chip->base + REG_TCFG1);
+	reg >>= TCFG1_SHIFT(chan);
+	reg &= TCFG1_MUX_MASK;
+
+	return ((1 << reg) & variant->tclk_mask) == 0;
+}
+
+static unsigned long pwm_samsung_get_tin_rate(struct samsung_pwm_chip *chip,
+							unsigned int chan)
+{
+	unsigned long rate;
+	u32 reg;
+
+	rate = clk_get_rate(chip->base_clk);
+
+	reg = readl(chip->base + REG_TCFG0);
+	if (chan >= 2)
+		reg >>= TCFG0_PRESCALER1_SHIFT;
+	reg &= TCFG0_PRESCALER_MASK;
+
+	return rate / (reg + 1);
+}
+
+static unsigned long pwm_samsung_calc_tin(struct samsung_pwm_chip *chip,
+					unsigned int chan, unsigned long freq)
+{
+	struct samsung_pwm_variant *variant = &chip->variant;
+	unsigned long rate;
+	unsigned int div;
+	struct clk *clk;
+
+	if (!pwm_samsung_is_tdiv(chip, chan)) {
+		clk = (chan < 2) ? chip->tclk0 : chip->tclk1;
+		if (!IS_ERR(clk)) {
+			rate = clk_get_rate(clk);
+			if (rate)
+				return rate;
+		}
+
+		dev_warn(chip->chip.dev,
+			"tclk of PWM %d is inoperational, using tdiv\n", chan);
+	}
+
+	rate = pwm_samsung_get_tin_rate(chip, chan);
+	dev_dbg(chip->chip.dev, "tin parent at %lu\n", rate);
+
+	/*
+	 * Compare minimum PWM frequency that can be achieved with possible
+	 * divider settings and choose the lowest divisor that can generate
+	 * frequencies lower than requested.
+	 */
+	for (div = variant->div_base; div < 4; ++div)
+		if ((rate >> (variant->bits + div)) < freq)
+			break;
+
+	pwm_samsung_set_divisor(chip, chan, 1 << div);
+
+	return rate >> div;
+}
+
+static int pwm_samsung_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
+
+	if (our_chip->variant.output_mask & (1 << pwm->hwpwm))
+		return 0;
+
+	dev_warn(our_chip->chip.dev,
+			"tried to request PWM channel %d without output\n",
+			pwm->hwpwm);
+
+	return -EINVAL;
+}
+
+static int pwm_samsung_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
+	unsigned int channel = pwm->hwpwm;
+	unsigned long tcon;
+	unsigned long flags;
+
+	if (channel > 0)
+		++channel;
+
+	spin_lock_irqsave(&samsung_pwm_lock, flags);
+
+	tcon = __raw_readl(our_chip->base + REG_TCON);
+
+	tcon &= ~TCON_MANUALUPDATE(channel);
+	tcon |= TCON_START(channel) | TCON_AUTORELOAD(channel);
+
+	__raw_writel(tcon, our_chip->base + REG_TCON);
+
+	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
+
+	return 0;
+}
+
+static void pwm_samsung_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
+	unsigned int channel = pwm->hwpwm;
+	unsigned long tcon;
+	unsigned long flags;
+
+	if (channel > 0)
+		++channel;
+
+	spin_lock_irqsave(&samsung_pwm_lock, flags);
+
+	tcon = __raw_readl(our_chip->base + REG_TCON);
+	tcon &= ~TCON_AUTORELOAD(channel);
+	__raw_writel(tcon, our_chip->base + REG_TCON);
+
+	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
+}
+
+static int pwm_samsung_config(struct pwm_chip *chip, struct pwm_device *pwm,
+		int duty_ns, int period_ns)
+{
+	struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
+	struct samsung_pwm_channel *chan = &our_chip->channels[pwm->hwpwm];
+	unsigned long tin_ns = chan->tin_ns;
+	unsigned int tcon_chan = pwm->hwpwm;
+	unsigned long tin_rate;
+	unsigned long period;
+	unsigned long flags;
+	unsigned long tcnt;
+	long tcmp;
+	u32 tcon;
+
+	/* We currently avoid using 64bit arithmetic by using the
+	 * fact that anything faster than 1Hz is easily representable
+	 * by 32bits. */
+	if (period_ns > NSEC_PER_SEC || duty_ns > NSEC_PER_SEC)
+		return -ERANGE;
+
+	if (period_ns == chan->period_ns && duty_ns == chan->duty_ns)
+		return 0;
+
+	/* The TCMP and TCNT can be read without a lock, they're not
+	 * shared between the timers. */
+	tcmp = readl(our_chip->base + REG_TCMPB(pwm->hwpwm));
+	tcnt = readl(our_chip->base + REG_TCNTB(pwm->hwpwm));
+
+	period = NSEC_PER_SEC / period_ns;
+
+	dev_dbg(our_chip->chip.dev, "duty_ns=%d, period_ns=%d (%lu)\n",
+		duty_ns, period_ns, period);
+
+	/* Check to see if we are changing the clock rate of the PWM */
+	if (chan->period_ns != period_ns) {
+		tin_rate = pwm_samsung_calc_tin(our_chip, pwm->hwpwm, period);
+
+		chan->period_ns = period_ns;
+
+		dev_dbg(our_chip->chip.dev, "tin_rate=%lu\n", tin_rate);
+
+		tin_ns = NSEC_PER_SEC / tin_rate;
+		tcnt = period_ns / tin_ns;
+
+		chan->tin_ns = tin_ns;
+	}
+
+	/* Note, counters count down */
+	tcmp = duty_ns / tin_ns;
+	tcmp = tcnt - tcmp;
+
+	/* the pwm hw only checks the compare register after a decrement,
+	   so the pin never toggles if tcmp = tcnt */
+	if (tcmp == tcnt)
+		tcmp--;
+
+	dev_dbg(our_chip->chip.dev, "tin_ns=%lu, tcmp=%ld/%lu\n",
+							tin_ns, tcmp, tcnt);
+
+	if (tcmp < 0)
+		tcmp = 0;
+
+	/* Update the PWM register block. */
+	if (tcon_chan > 0)
+		++tcon_chan;
+
+	spin_lock_irqsave(&samsung_pwm_lock, flags);
+
+	tcon = __raw_readl(our_chip->base + REG_TCON);
+
+	tcnt--;
+
+	tcon &= ~(TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan));
+	tcon |= TCON_MANUALUPDATE(tcon_chan);
+
+	__raw_writel(tcnt, our_chip->base + REG_TCNTB(pwm->hwpwm));
+	__raw_writel(tcmp, our_chip->base + REG_TCMPB(pwm->hwpwm));
+	__raw_writel(tcon, our_chip->base + REG_TCON);
+
+	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
+
+	return 0;
+}
+
+static int pwm_samsung_set_polarity(struct pwm_chip *chip,
+			struct pwm_device *pwm, enum pwm_polarity polarity)
+{
+	struct samsung_pwm_chip *our_chip = to_samsung_pwm_chip(chip);
+	unsigned int channel = pwm->hwpwm;
+	unsigned long flags;
+	u32 tcon;
+
+	if (channel > 0)
+		++channel;
+
+	spin_lock_irqsave(&samsung_pwm_lock, flags);
+
+	tcon = __raw_readl(our_chip->base + REG_TCON);
+
+	/* Invert in hardware means normal polarity of PWM core */
+	if (polarity == PWM_POLARITY_NORMAL)
+		tcon |= TCON_INVERT(channel);
+	else
+		tcon &= ~TCON_INVERT(channel);
+
+	__raw_writel(tcon, our_chip->base + REG_TCON);
+
+	spin_unlock_irqrestore(&samsung_pwm_lock, flags);
+
+	return 0;
+}
+
+static struct pwm_ops pwm_samsung_ops = {
+	.request	= pwm_samsung_request,
+	.enable		= pwm_samsung_enable,
+	.disable	= pwm_samsung_disable,
+	.config		= pwm_samsung_config,
+	.set_polarity	= pwm_samsung_set_polarity,
+	.owner		= THIS_MODULE,
+};
+
+#ifdef CONFIG_OF
+static const struct samsung_pwm_variant s3c24xx_variant = {
+	.bits		= 16,
+	.div_base	= 1,
+	.has_tint_cstat	= false,
+	.tclk_mask	= (1 << 4),
+};
+
+static const struct samsung_pwm_variant s3c64xx_variant = {
+	.bits		= 32,
+	.div_base	= 0,
+	.has_tint_cstat	= true,
+	.tclk_mask	= (1 << 7) | (1 << 6) | (1 << 5),
+};
+
+static const struct samsung_pwm_variant s5p64x0_variant = {
+	.bits		= 32,
+	.div_base	= 0,
+	.has_tint_cstat	= true,
+	.tclk_mask	= 0,
+};
+
+static const struct samsung_pwm_variant s5p_variant = {
+	.bits		= 32,
+	.div_base	= 0,
+	.has_tint_cstat	= true,
+	.tclk_mask	= (1 << 5),
+};
+
+static const struct of_device_id samsung_pwm_matches[] = {
+	{ .compatible = "samsung,s3c2410-pwm", .data = &s3c24xx_variant },
+	{ .compatible = "samsung,s3c6400-pwm", .data = &s3c64xx_variant },
+	{ .compatible = "samsung,s5p6440-pwm", .data = &s5p64x0_variant },
+	{ .compatible = "samsung,s5pc100-pwm", .data = &s5p_variant },
+	{ .compatible = "samsung,exynos4210-pwm", .data = &s5p64x0_variant },
+	{},
+};
+#endif
+
+static int pwm_samsung_parse_dt(struct samsung_pwm_chip *chip)
+{
+	struct device_node *np = chip->chip.dev->of_node;
+	const struct of_device_id *match;
+	struct property *prop;
+	const __be32 *cur;
+	u32 val;
+
+	match = of_match_node(samsung_pwm_matches, np);
+	if (!match)
+		return -ENODEV;
+
+	memcpy(&chip->variant, match->data, sizeof(chip->variant));
+
+	of_property_for_each_u32(np, "samsung,pwm-outputs", prop, cur, val) {
+		if (val >= SAMSUNG_PWM_NUM) {
+			pr_warning("%s: invalid channel index in samsung,pwm-outputs property\n",
+								__func__);
+			continue;
+		}
+		chip->variant.output_mask |= 1 << val;
+	}
+
+	return 0;
+}
+
+static int pwm_samsung_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct samsung_pwm_chip *chip;
+	struct resource *res;
+	int ret;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (chip == NULL) {
+		dev_err(dev, "failed to allocate driver data\n");
+		return -ENOMEM;
+	}
+
+	chip->chip.dev = &pdev->dev;
+	chip->chip.ops = &pwm_samsung_ops;
+	chip->chip.base = -1;
+	chip->chip.npwm = SAMSUNG_PWM_NUM;
+
+	if (pdev->dev.of_node) {
+		ret = pwm_samsung_parse_dt(chip);
+		if (ret)
+			return ret;
+
+		chip->chip.of_xlate = of_pwm_xlate_with_flags;
+		chip->chip.of_pwm_n_cells = 3;
+	} else {
+		if (!pdev->dev.platform_data) {
+			dev_err(&pdev->dev, "no platform data specified\n");
+			return -EINVAL;
+		}
+
+		memcpy(&chip->variant, pdev->dev.platform_data,
+							sizeof(chip->variant));
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "failed to get mem resource\n");
+		return -ENOMEM;
+	}
+
+	chip->base = devm_request_and_ioremap(&pdev->dev, res);
+	if (!chip->base) {
+		dev_err(&pdev->dev, "failed to request and map registers\n");
+		return -ENOMEM;
+	}
+
+	chip->base_clk = devm_clk_get(&pdev->dev, "timers");
+	if (IS_ERR(chip->base_clk)) {
+		dev_err(dev, "failed to get timer base clk\n");
+		return PTR_ERR(chip->base_clk);
+	}
+	clk_prepare_enable(chip->base_clk);
+
+	chip->tclk0 = devm_clk_get(&pdev->dev, "pwm-tclk0");
+	chip->tclk1 = devm_clk_get(&pdev->dev, "pwm-tclk1");
+
+	ret = pwmchip_add(&chip->chip);
+	if (ret < 0) {
+		dev_err(dev, "failed to register pwm\n");
+		goto err_clk_disable;
+	}
+
+	dev_info(dev, "base_clk at %lu, tclk0 at %lu, tclk1 at %lu\n",
+		clk_get_rate(chip->base_clk),
+		!IS_ERR(chip->tclk0) ? clk_get_rate(chip->tclk0) : 0,
+		!IS_ERR(chip->tclk1) ? clk_get_rate(chip->tclk1) : 0);
+
+	platform_set_drvdata(pdev, chip);
+
+	return 0;
+
+err_clk_disable:
+	clk_disable_unprepare(chip->base_clk);
+
+	return ret;
+}
+
+static int pwm_samsung_remove(struct platform_device *pdev)
+{
+	struct samsung_pwm_chip *chip = platform_get_drvdata(pdev);
+	int err;
+
+	err = pwmchip_remove(&chip->chip);
+	if (err < 0)
+		return err;
+
+	clk_disable_unprepare(chip->base_clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int pwm_samsung_suspend(struct device *dev)
+{
+	struct samsung_pwm_chip *chip = dev_get_drvdata(dev);
+	int i;
+
+	/* No one preserve these values during suspend so reset them
+	 * Otherwise driver leaves PWM unconfigured if same values
+	 * passed to pwm_config
+	 */
+	for (i = 0; i < SAMSUNG_PWM_NUM; ++i) {
+		chip->channels[i].period_ns = 0;
+		chip->channels[i].duty_ns = 0;
+	}
+
+	return 0;
+}
+#endif
+
+static struct dev_pm_ops pwm_samsung_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(pwm_samsung_suspend, NULL)
+};
+
+static struct platform_driver pwm_samsung_driver = {
+	.driver		= {
+		.name	= "samsung-pwm",
+		.owner	= THIS_MODULE,
+		.pm	= &pwm_samsung_pm_ops,
+		.of_match_table = of_match_ptr(samsung_pwm_matches),
+	},
+	.probe		= pwm_samsung_probe,
+	.remove		= pwm_samsung_remove,
+};
+module_platform_driver(pwm_samsung_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Tomasz Figa <tomasz.figa at gmail.com>");
+MODULE_ALIAS("platform:samsung-pwm");
-- 
1.8.2.1




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