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authorTomasz Figa <tomasz.figa@gmail.com>2013-04-06 02:40:36 +0200
committerTomasz Figa <tomasz.figa@gmail.com>2013-08-12 21:53:22 +0200
commit11ad39ede24ee42909d58dc95031d96da46e33bd (patch)
tree3de054343ca1712338b7a2526d1bac460e0f6cb2 /drivers/pwm/pwm-samsung.c
parent615c19e1607be1586aa2848712770423288c4f0e (diff)
pwm: Add new pwm-samsung driver
This patch introduces new Samsung PWM driver, which is completely rewritten to be multiplatform- and DeviceTree-aware. In addition, remaining problems of old driver are fixed, such as: - proper handling of hardware variants, - synchronization on SMP systems, - handling of boundary parameter values, - hardware sharing with PWM clocksource driver, - undefined state of PWM output after stopping PWM channel. Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com> Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com> Tested-by: Heiko Stuebner <heiko@sntech.de> Tested-by: Mark Brown <broonie@linaro.org> Tested-by: Sylwester Nawrocki <sylvester.nawrocki@gmail.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm/pwm-samsung.c')
-rw-r--r--drivers/pwm/pwm-samsung.c618
1 files changed, 618 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-samsung.c b/drivers/pwm/pwm-samsung.c
new file mode 100644
index 000000000000..fcc8b9adde9f
--- /dev/null
+++ b/drivers/pwm/pwm-samsung.c
@@ -0,0 +1,618 @@
+/*
+ * Copyright (c) 2007 Ben Dooks
+ * Copyright (c) 2008 Simtec Electronics
+ * Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
+ * Copyright (c) 2013 Tomasz Figa <tomasz.figa@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/bitops.h>
+#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>
+
+/* For struct samsung_timer_variant and samsung_pwm_lock. */
+#include <clocksource/samsung_pwm.h>
+
+#define REG_TCFG0 0x00
+#define REG_TCFG1 0x04
+#define REG_TCON 0x08
+
+#define REG_TCNTB(chan) (0x0c + ((chan) * 0xc))
+#define REG_TCMPB(chan) (0x10 + ((chan) * 0xc))
+
+#define TCFG0_PRESCALER_MASK 0xff
+#define TCFG0_PRESCALER1_SHIFT 8
+
+#define TCFG1_MUX_MASK 0xf
+#define TCFG1_SHIFT(chan) (4 * (chan))
+
+/*
+ * Each channel occupies 4 bits in TCON register, but there is a gap of 4
+ * bits (one channel) after channel 0, so channels have different numbering
+ * when accessing TCON register. See to_tcon_channel() function.
+ *
+ * In addition, the location of autoreload bit for channel 4 (TCON channel 5)
+ * in its set of bits is 2 as opposed to 3 for other channels.
+ */
+#define TCON_START(chan) BIT(4 * (chan) + 0)
+#define TCON_MANUALUPDATE(chan) BIT(4 * (chan) + 1)
+#define TCON_INVERT(chan) BIT(4 * (chan) + 2)
+#define _TCON_AUTORELOAD(chan) BIT(4 * (chan) + 3)
+#define _TCON_AUTORELOAD4(chan) BIT(4 * (chan) + 2)
+#define TCON_AUTORELOAD(chan) \
+ ((chan < 5) ? _TCON_AUTORELOAD(chan) : _TCON_AUTORELOAD4(chan))
+
+/**
+ * struct samsung_pwm_channel - private data of PWM channel
+ * @period_ns: current period in nanoseconds programmed to the hardware
+ * @duty_ns: current duty time in nanoseconds programmed to the hardware
+ * @tin_ns: time of one timer tick in nanoseconds with current timer rate
+ */
+struct samsung_pwm_channel {
+ u32 period_ns;
+ u32 duty_ns;
+ u32 tin_ns;
+};
+
+/**
+ * struct samsung_pwm_chip - private data of PWM chip
+ * @chip: generic PWM chip
+ * @variant: local copy of hardware variant data
+ * @inverter_mask: inverter status for all channels - one bit per channel
+ * @base: base address of mapped PWM registers
+ * @base_clk: base clock used to drive the timers
+ * @tclk0: external clock 0 (can be ERR_PTR if not present)
+ * @tclk1: external clock 1 (can be ERR_PTR if not present)
+ */
+struct samsung_pwm_chip {
+ struct pwm_chip chip;
+ struct samsung_pwm_variant variant;
+ u8 inverter_mask;
+
+ void __iomem *base;
+ struct clk *base_clk;
+ struct clk *tclk0;
+ struct clk *tclk1;
+};
+
+#ifndef CONFIG_CLKSRC_SAMSUNG_PWM
+/*
+ * PWM block is shared between pwm-samsung and samsung_pwm_timer drivers
+ * and some registers need access synchronization. If both drivers are
+ * compiled in, the spinlock is defined in the clocksource driver,
+ * otherwise following definition is used.
+ *
+ * Currently we do not need any more complex synchronization method
+ * because all the supported SoCs contain only one instance of the PWM
+ * IP. Should this change, both drivers will need to be modified to
+ * properly synchronize accesses to particular instances.
+ */
+static DEFINE_SPINLOCK(samsung_pwm_lock);
+#endif
+
+static inline
+struct samsung_pwm_chip *to_samsung_pwm_chip(struct pwm_chip *chip)
+{
+ return container_of(chip, struct samsung_pwm_chip, chip);
+}
+
+static inline unsigned int to_tcon_channel(unsigned int channel)
+{
+ /* TCON register has a gap of 4 bits (1 channel) after channel 0 */
+ return (channel == 0) ? 0 : (channel + 1);
+}
+
+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 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 (BIT(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;
+ struct clk *clk;
+ u8 div;
+
+ 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, BIT(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);
+ struct samsung_pwm_channel *our_chan;
+
+ if (!(our_chip->variant.output_mask & BIT(pwm->hwpwm))) {
+ dev_warn(chip->dev,
+ "tried to request PWM channel %d without output\n",
+ pwm->hwpwm);
+ return -EINVAL;
+ }
+
+ our_chan = devm_kzalloc(chip->dev, sizeof(*our_chan), GFP_KERNEL);
+ if (!our_chan)
+ return -ENOMEM;
+
+ pwm_set_chip_data(pwm, our_chan);
+
+ return 0;
+}
+
+static void pwm_samsung_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ pwm_set_chip_data(pwm, NULL);
+ devm_kfree(chip->dev, pwm_get_chip_data(pwm));
+}
+
+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 tcon_chan = to_tcon_channel(pwm->hwpwm);
+ unsigned long flags;
+ u32 tcon;
+
+ spin_lock_irqsave(&samsung_pwm_lock, flags);
+
+ tcon = readl(our_chip->base + REG_TCON);
+
+ tcon &= ~TCON_START(tcon_chan);
+ tcon |= TCON_MANUALUPDATE(tcon_chan);
+ writel(tcon, our_chip->base + REG_TCON);
+
+ tcon &= ~TCON_MANUALUPDATE(tcon_chan);
+ tcon |= TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan);
+ 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 tcon_chan = to_tcon_channel(pwm->hwpwm);
+ unsigned long flags;
+ u32 tcon;
+
+ spin_lock_irqsave(&samsung_pwm_lock, flags);
+
+ tcon = readl(our_chip->base + REG_TCON);
+ tcon &= ~TCON_AUTORELOAD(tcon_chan);
+ 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 = pwm_get_chip_data(pwm);
+ u32 tin_ns = chan->tin_ns, tcnt, tcmp;
+
+ /*
+ * 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)
+ return -ERANGE;
+
+ if (period_ns == chan->period_ns && duty_ns == chan->duty_ns)
+ return 0;
+
+ tcnt = readl(our_chip->base + REG_TCNTB(pwm->hwpwm));
+
+ /* We need tick count for calculation, not last tick. */
+ ++tcnt;
+
+ /* Check to see if we are changing the clock rate of the PWM. */
+ if (chan->period_ns != period_ns) {
+ unsigned long tin_rate;
+ u32 period;
+
+ period = NSEC_PER_SEC / period_ns;
+
+ dev_dbg(our_chip->chip.dev, "duty_ns=%d, period_ns=%d (%u)\n",
+ duty_ns, period_ns, period);
+
+ tin_rate = pwm_samsung_calc_tin(our_chip, pwm->hwpwm, period);
+
+ dev_dbg(our_chip->chip.dev, "tin_rate=%lu\n", tin_rate);
+
+ tin_ns = NSEC_PER_SEC / tin_rate;
+ tcnt = period_ns / tin_ns;
+ }
+
+ /* Period is too short. */
+ if (tcnt <= 1)
+ return -ERANGE;
+
+ /* Note that counters count down. */
+ tcmp = duty_ns / tin_ns;
+
+ /* 0% duty is not available */
+ if (!tcmp)
+ ++tcmp;
+
+ tcmp = tcnt - tcmp;
+
+ /* Decrement to get tick numbers, instead of tick counts. */
+ --tcnt;
+ /* -1UL will give 100% duty. */
+ --tcmp;
+
+ dev_dbg(our_chip->chip.dev,
+ "tin_ns=%u, tcmp=%u/%u\n", tin_ns, tcmp, tcnt);
+
+ /* Update PWM registers. */
+ writel(tcnt, our_chip->base + REG_TCNTB(pwm->hwpwm));
+ writel(tcmp, our_chip->base + REG_TCMPB(pwm->hwpwm));
+
+ if (test_bit(PWMF_ENABLED, &pwm->flags))
+ pwm_samsung_enable(chip, pwm);
+
+ chan->period_ns = period_ns;
+ chan->tin_ns = tin_ns;
+ chan->duty_ns = duty_ns;
+
+ return 0;
+}
+
+static void pwm_samsung_set_invert(struct samsung_pwm_chip *chip,
+ unsigned int channel, bool invert)
+{
+ unsigned int tcon_chan = to_tcon_channel(channel);
+ unsigned long flags;
+ u32 tcon;
+
+ spin_lock_irqsave(&samsung_pwm_lock, flags);
+
+ tcon = readl(chip->base + REG_TCON);
+
+ if (invert) {
+ chip->inverter_mask |= BIT(channel);
+ tcon |= TCON_INVERT(tcon_chan);
+ } else {
+ chip->inverter_mask &= ~BIT(channel);
+ tcon &= ~TCON_INVERT(tcon_chan);
+ }
+
+ writel(tcon, chip->base + REG_TCON);
+
+ spin_unlock_irqrestore(&samsung_pwm_lock, flags);
+}
+
+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);
+ bool invert = (polarity == PWM_POLARITY_NORMAL);
+
+ /* Inverted means normal in the hardware. */
+ pwm_samsung_set_invert(our_chip, pwm->hwpwm, invert);
+
+ return 0;
+}
+
+static const struct pwm_ops pwm_samsung_ops = {
+ .request = pwm_samsung_request,
+ .free = pwm_samsung_free,
+ .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 = BIT(4),
+};
+
+static const struct samsung_pwm_variant s3c64xx_variant = {
+ .bits = 32,
+ .div_base = 0,
+ .has_tint_cstat = true,
+ .tclk_mask = BIT(7) | BIT(6) | BIT(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 s5pc100_variant = {
+ .bits = 32,
+ .div_base = 0,
+ .has_tint_cstat = true,
+ .tclk_mask = BIT(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 = &s5pc100_variant },
+ { .compatible = "samsung,exynos4210-pwm", .data = &s5p64x0_variant },
+ {},
+};
+
+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) {
+ dev_err(chip->chip.dev,
+ "%s: invalid channel index in samsung,pwm-outputs property\n",
+ __func__);
+ continue;
+ }
+ chip->variant.output_mask |= BIT(val);
+ }
+
+ return 0;
+}
+#else
+static int pwm_samsung_parse_dt(struct samsung_pwm_chip *chip)
+{
+ return -ENODEV;
+}
+#endif
+
+static int pwm_samsung_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct samsung_pwm_chip *chip;
+ struct resource *res;
+ unsigned int chan;
+ int ret;
+
+ chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+ if (chip == NULL)
+ return -ENOMEM;
+
+ chip->chip.dev = &pdev->dev;
+ chip->chip.ops = &pwm_samsung_ops;
+ chip->chip.base = -1;
+ chip->chip.npwm = SAMSUNG_PWM_NUM;
+ chip->inverter_mask = BIT(SAMSUNG_PWM_NUM) - 1;
+
+ if (IS_ENABLED(CONFIG_OF) && 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);
+ chip->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(chip->base))
+ return PTR_ERR(chip->base);
+
+ 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);
+ }
+
+ ret = clk_prepare_enable(chip->base_clk);
+ if (ret < 0) {
+ dev_err(dev, "failed to enable base clock\n");
+ return ret;
+ }
+
+ for (chan = 0; chan < SAMSUNG_PWM_NUM; ++chan)
+ if (chip->variant.output_mask & BIT(chan))
+ pwm_samsung_set_invert(chip, chan, true);
+
+ /* Following clocks are optional. */
+ chip->tclk0 = devm_clk_get(&pdev->dev, "pwm-tclk0");
+ chip->tclk1 = devm_clk_get(&pdev->dev, "pwm-tclk1");
+
+ platform_set_drvdata(pdev, chip);
+
+ ret = pwmchip_add(&chip->chip);
+ if (ret < 0) {
+ dev_err(dev, "failed to register PWM chip\n");
+ clk_disable_unprepare(chip->base_clk);
+ return ret;
+ }
+
+ dev_dbg(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);
+
+ return 0;
+}
+
+static int pwm_samsung_remove(struct platform_device *pdev)
+{
+ struct samsung_pwm_chip *chip = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = pwmchip_remove(&chip->chip);
+ if (ret < 0)
+ return ret;
+
+ clk_disable_unprepare(chip->base_clk);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int pwm_samsung_suspend(struct device *dev)
+{
+ struct samsung_pwm_chip *chip = dev_get_drvdata(dev);
+ unsigned int i;
+
+ /*
+ * No one preserves these values during suspend so reset them.
+ * Otherwise driver leaves PWM unconfigured if same values are
+ * passed to pwm_config() next time.
+ */
+ for (i = 0; i < SAMSUNG_PWM_NUM; ++i) {
+ struct pwm_device *pwm = &chip->chip.pwms[i];
+ struct samsung_pwm_channel *chan = pwm_get_chip_data(pwm);
+
+ if (!chan)
+ continue;
+
+ chan->period_ns = 0;
+ chan->duty_ns = 0;
+ }
+
+ return 0;
+}
+
+static int pwm_samsung_resume(struct device *dev)
+{
+ struct samsung_pwm_chip *chip = dev_get_drvdata(dev);
+ unsigned int chan;
+
+ /*
+ * Inverter setting must be preserved across suspend/resume
+ * as nobody really seems to configure it more than once.
+ */
+ for (chan = 0; chan < SAMSUNG_PWM_NUM; ++chan) {
+ if (chip->variant.output_mask & BIT(chan))
+ pwm_samsung_set_invert(chip, chan,
+ chip->inverter_mask & BIT(chan));
+ }
+
+ return 0;
+}
+#endif
+
+static const struct dev_pm_ops pwm_samsung_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(pwm_samsung_suspend, pwm_samsung_resume)
+};
+
+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@gmail.com>");
+MODULE_ALIAS("platform:samsung-pwm");

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