--- /dev/null
+/*
+ * PWM device driver for ST SoCs.
+ * Author: Ajit Pal Singh <ajitpal.singh@st.com>
+ *
+ * Copyright (C) 2013-2014 STMicroelectronics (R&D) Limited
+ *
+ * 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.
+ */
+
+#include <linux/clk.h>
+#include <linux/math64.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+
+#define STI_DS_REG(ch) (4 * (ch)) /* Channel's Duty Cycle register */
+#define STI_PWMCR 0x50 /* Control/Config register */
+#define STI_INTEN 0x54 /* Interrupt Enable/Disable register */
+#define PWM_PRESCALE_LOW_MASK 0x0f
+#define PWM_PRESCALE_HIGH_MASK 0xf0
+
+/* Regfield IDs */
+enum {
+ PWMCLK_PRESCALE_LOW,
+ PWMCLK_PRESCALE_HIGH,
+ PWM_EN,
+ PWM_INT_EN,
+
+ /* Keep last */
+ MAX_REGFIELDS
+};
+
+struct sti_pwm_compat_data {
+ const struct reg_field *reg_fields;
+ unsigned int num_chan;
+ unsigned int max_pwm_cnt;
+ unsigned int max_prescale;
+};
+
+struct sti_pwm_chip {
+ struct device *dev;
+ struct clk *clk;
+ unsigned long clk_rate;
+ struct regmap *regmap;
+ struct sti_pwm_compat_data *cdata;
+ struct regmap_field *prescale_low;
+ struct regmap_field *prescale_high;
+ struct regmap_field *pwm_en;
+ struct regmap_field *pwm_int_en;
+ struct pwm_chip chip;
+ struct pwm_device *cur;
+ unsigned long configured;
+ unsigned int en_count;
+ struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
+ void __iomem *mmio;
+};
+
+static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
+ [PWMCLK_PRESCALE_LOW] = REG_FIELD(STI_PWMCR, 0, 3),
+ [PWMCLK_PRESCALE_HIGH] = REG_FIELD(STI_PWMCR, 11, 14),
+ [PWM_EN] = REG_FIELD(STI_PWMCR, 9, 9),
+ [PWM_INT_EN] = REG_FIELD(STI_INTEN, 0, 0),
+};
+
+static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
+{
+ return container_of(chip, struct sti_pwm_chip, chip);
+}
+
+/*
+ * Calculate the prescaler value corresponding to the period.
+ */
+static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
+ unsigned int *prescale)
+{
+ struct sti_pwm_compat_data *cdata = pc->cdata;
+ unsigned long val;
+ unsigned int ps;
+
+ /*
+ * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_count + 1)) - 1
+ */
+ val = NSEC_PER_SEC / pc->clk_rate;
+ val *= cdata->max_pwm_cnt + 1;
+
+ if (period % val) {
+ return -EINVAL;
+ } else {
+ ps = period / val - 1;
+ if (ps > cdata->max_prescale)
+ return -EINVAL;
+ }
+ *prescale = ps;
+
+ return 0;
+}
+
+/*
+ * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles.
+ * The only way to change the period (apart from changing the PWM input clock)
+ * is to change the PWM clock prescaler.
+ * The prescaler is of 8 bits, so 256 prescaler values and hence
+ * 256 possible period values are supported (for a particular clock rate).
+ * The requested period will be applied only if it matches one of these
+ * 256 values.
+ */
+static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
+ int duty_ns, int period_ns)
+{
+ struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+ struct sti_pwm_compat_data *cdata = pc->cdata;
+ struct pwm_device *cur = pc->cur;
+ struct device *dev = pc->dev;
+ unsigned int prescale = 0, pwmvalx;
+ int ret;
+ unsigned int ncfg;
+ bool period_same = false;
+
+ ncfg = hweight_long(pc->configured);
+ if (ncfg)
+ period_same = (period_ns == pwm_get_period(cur));
+
+ /* Allow configuration changes if one of the
+ * following conditions satisfy.
+ * 1. No channels have been configured.
+ * 2. Only one channel has been configured and the new request
+ * is for the same channel.
+ * 3. Only one channel has been configured and the new request is
+ * for a new channel and period of the new channel is same as
+ * the current configured period.
+ * 4. More than one channels are configured and period of the new
+ * requestis the same as the current period.
+ */
+ if (!ncfg ||
+ ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
+ ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
+ ((ncfg > 1) && period_same)) {
+ /* Enable clock before writing to PWM registers. */
+ ret = clk_enable(pc->clk);
+ if (ret)
+ return ret;
+
+ if (!period_same) {
+ ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
+ if (ret)
+ goto clk_dis;
+
+ ret =
+ regmap_field_write(pc->prescale_low,
+ prescale & PWM_PRESCALE_LOW_MASK);
+ if (ret)
+ goto clk_dis;
+
+ ret =
+ regmap_field_write(pc->prescale_high,
+ (prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
+ if (ret)
+ goto clk_dis;
+ }
+
+ /*
+ * When PWMVal == 0, PWM pulse = 1 local clock cycle.
+ * When PWMVal == max_pwm_count,
+ * PWM pulse = (max_pwm_count + 1) local cycles,
+ * that is continuous pulse: signal never goes low.
+ */
+ pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;
+
+ ret = regmap_write(pc->regmap, STI_DS_REG(pwm->hwpwm), pwmvalx);
+ if (ret)
+ goto clk_dis;
+
+ ret = regmap_field_write(pc->pwm_int_en, 0);
+
+ set_bit(pwm->hwpwm, &pc->configured);
+ pc->cur = pwm;
+
+ dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
+ prescale, period_ns, duty_ns, pwmvalx);
+ } else {
+ return -EINVAL;
+ }
+
+clk_dis:
+ clk_disable(pc->clk);
+ return ret;
+}
+
+static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+ struct device *dev = pc->dev;
+ int ret = 0;
+
+ /*
+ * Since we have a common enable for all PWM channels,
+ * do not enable if already enabled.
+ */
+ mutex_lock(&pc->sti_pwm_lock);
+ if (!pc->en_count) {
+ ret = clk_enable(pc->clk);
+ if (ret)
+ goto out;
+
+ ret = regmap_field_write(pc->pwm_en, 1);
+ if (ret) {
+ dev_err(dev, "failed to enable PWM device:%d\n",
+ pwm->hwpwm);
+ goto out;
+ }
+ }
+ pc->en_count++;
+out:
+ mutex_unlock(&pc->sti_pwm_lock);
+ return ret;
+}
+
+static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+
+ mutex_lock(&pc->sti_pwm_lock);
+ if (--pc->en_count) {
+ mutex_unlock(&pc->sti_pwm_lock);
+ return;
+ }
+ regmap_field_write(pc->pwm_en, 0);
+
+ clk_disable(pc->clk);
+ mutex_unlock(&pc->sti_pwm_lock);
+}
+
+static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+
+ clear_bit(pwm->hwpwm, &pc->configured);
+}
+
+static const struct pwm_ops sti_pwm_ops = {
+ .config = sti_pwm_config,
+ .enable = sti_pwm_enable,
+ .disable = sti_pwm_disable,
+ .free = sti_pwm_free,
+ .owner = THIS_MODULE,
+};
+
+static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
+{
+ struct device *dev = pc->dev;
+ const struct reg_field *reg_fields;
+ struct device_node *np = dev->of_node;
+ struct sti_pwm_compat_data *cdata = pc->cdata;
+ u32 num_chan;
+
+ of_property_read_u32(np, "st,pwm-num-chan", &num_chan);
+ if (num_chan)
+ cdata->num_chan = num_chan;
+
+ reg_fields = cdata->reg_fields;
+
+ pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
+ reg_fields[PWMCLK_PRESCALE_LOW]);
+ if (IS_ERR(pc->prescale_low))
+ return PTR_ERR(pc->prescale_low);
+
+ pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
+ reg_fields[PWMCLK_PRESCALE_HIGH]);
+ if (IS_ERR(pc->prescale_high))
+ return PTR_ERR(pc->prescale_high);
+
+ pc->pwm_en = devm_regmap_field_alloc(dev, pc->regmap,
+ reg_fields[PWM_EN]);
+ if (IS_ERR(pc->pwm_en))
+ return PTR_ERR(pc->pwm_en);
+
+ pc->pwm_int_en = devm_regmap_field_alloc(dev, pc->regmap,
+ reg_fields[PWM_INT_EN]);
+ if (IS_ERR(pc->pwm_int_en))
+ return PTR_ERR(pc->pwm_int_en);
+
+ return 0;
+}
+
+static const struct regmap_config sti_pwm_regmap_config = {
+ .reg_bits = 32,
+ .val_bits = 32,
+ .reg_stride = 4,
+};
+
+static int sti_pwm_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct sti_pwm_compat_data *cdata;
+ struct sti_pwm_chip *pc;
+ struct resource *res;
+ int ret;
+
+ pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
+ if (!pc)
+ return -ENOMEM;
+
+ cdata = devm_kzalloc(dev, sizeof(*cdata), GFP_KERNEL);
+ if (!cdata)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+ pc->mmio = devm_ioremap_resource(dev, res);
+ if (IS_ERR(pc->mmio))
+ return PTR_ERR(pc->mmio);
+
+ pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
+ &sti_pwm_regmap_config);
+ if (IS_ERR(pc->regmap))
+ return PTR_ERR(pc->regmap);
+
+ /*
+ * Setup PWM data with default values: some values could be replaced
+ * with specific ones provided from Device Tree.
+ */
+ cdata->reg_fields = &sti_pwm_regfields[0];
+ cdata->max_prescale = 0xff;
+ cdata->max_pwm_cnt = 255;
+ cdata->num_chan = 1;
+
+ pc->cdata = cdata;
+ pc->dev = dev;
+ pc->en_count = 0;
+ mutex_init(&pc->sti_pwm_lock);
+
+ ret = sti_pwm_probe_dt(pc);
+ if (ret)
+ return ret;
+
+ pc->clk = of_clk_get_by_name(dev->of_node, "pwm");
+ if (IS_ERR(pc->clk)) {
+ dev_err(dev, "failed to get PWM clock\n");
+ return PTR_ERR(pc->clk);
+ }
+
+ pc->clk_rate = clk_get_rate(pc->clk);
+ if (!pc->clk_rate) {
+ dev_err(dev, "failed to get clock rate\n");
+ return -EINVAL;
+ }
+
+ ret = clk_prepare(pc->clk);
+ if (ret) {
+ dev_err(dev, "failed to prepare clock\n");
+ return ret;
+ }
+
+ pc->chip.dev = dev;
+ pc->chip.ops = &sti_pwm_ops;
+ pc->chip.base = -1;
+ pc->chip.npwm = pc->cdata->num_chan;
+ pc->chip.can_sleep = true;
+
+ ret = pwmchip_add(&pc->chip);
+ if (ret < 0) {
+ clk_unprepare(pc->clk);
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, pc);
+
+ return 0;
+}
+
+static int sti_pwm_remove(struct platform_device *pdev)
+{
+ struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
+ unsigned int i;
+
+ for (i = 0; i < pc->cdata->num_chan; i++)
+ pwm_disable(&pc->chip.pwms[i]);
+
+ clk_unprepare(pc->clk);
+
+ return pwmchip_remove(&pc->chip);
+}
+
+static const struct of_device_id sti_pwm_of_match[] = {
+ { .compatible = "st,sti-pwm", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, sti_pwm_of_match);
+
+static struct platform_driver sti_pwm_driver = {
+ .driver = {
+ .name = "sti-pwm",
+ .of_match_table = sti_pwm_of_match,
+ },
+ .probe = sti_pwm_probe,
+ .remove = sti_pwm_remove,
+};
+module_platform_driver(sti_pwm_driver);
+
+MODULE_AUTHOR("Ajit Pal Singh <ajitpal.singh@st.com>");
+MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff