diff options
author | Lee Jones <lee.jones@linaro.org> | 2014-07-14 15:33:27 +0100 |
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committer | Thierry Reding <thierry.reding@gmail.com> | 2014-08-07 16:18:27 +0200 |
commit | 378fe115d19d6ab9e9210a2ac330159afabf0237 (patch) | |
tree | 124bfe9199f10e722ef8578af4bb6ab69540efee /drivers/pwm | |
parent | 31c4fa3442570d001f58303dea36d81693bc199c (diff) | |
download | linux-378fe115d19d6ab9e9210a2ac330159afabf0237.tar.gz linux-378fe115d19d6ab9e9210a2ac330159afabf0237.tar.xz |
pwm: sti: Add new driver for ST's PWM IP
This driver supports all current STi platforms' PWM IPs.
Signed-off-by: Ajit Pal Singh <ajitpal.singh@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
[thierry.reding: rename module to pwm-sti, fix build breakage]
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm')
-rw-r--r-- | drivers/pwm/Kconfig | 10 | ||||
-rw-r--r-- | drivers/pwm/Makefile | 1 | ||||
-rw-r--r-- | drivers/pwm/pwm-sti.c | 366 |
3 files changed, 377 insertions, 0 deletions
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index a86879a313e4..fabd0c5cd6cc 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -233,6 +233,16 @@ config PWM_SPEAR To compile this driver as a module, choose M here: the module will be called pwm-spear. +config PWM_STI + tristate "STiH4xx PWM support" + depends on ARCH_STI + depends on OF + help + Generic PWM framework driver for STiH4xx SoCs. + + To compile this driver as a module, choose M here: the module + will be called pwm-sti. + config PWM_TEGRA tristate "NVIDIA Tegra PWM support" depends on ARCH_TEGRA diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index e03e2ae95791..f8c577d41091 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -21,6 +21,7 @@ obj-$(CONFIG_PWM_RENESAS_TPU) += pwm-renesas-tpu.o obj-$(CONFIG_PWM_ROCKCHIP) += pwm-rockchip.o obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o obj-$(CONFIG_PWM_SPEAR) += pwm-spear.o +obj-$(CONFIG_PWM_STI) += pwm-sti.o obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o obj-$(CONFIG_PWM_TIECAP) += pwm-tiecap.o obj-$(CONFIG_PWM_TIEHRPWM) += pwm-tiehrpwm.o diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c new file mode 100644 index 000000000000..0b714e45e5c0 --- /dev/null +++ b/drivers/pwm/pwm-sti.c @@ -0,0 +1,366 @@ +/* + * 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/bsearch.h> +#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 */ + +/* Regfield IDs */ +enum { + PWMCLK_PRESCALE, + 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; + struct regmap_field *pwm_en; + struct regmap_field *pwm_int_en; + unsigned long *pwm_periods; + struct pwm_chip chip; + void __iomem *mmio; +}; + +static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = { + [PWMCLK_PRESCALE] = REG_FIELD(STI_PWMCR, 0, 3), + [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 period values supported by the PWM for the + * current clock rate. + */ +static void sti_pwm_calc_periods(struct sti_pwm_chip *pc) +{ + struct sti_pwm_compat_data *cdata = pc->cdata; + struct device *dev = pc->dev; + unsigned long val; + int i; + + /* + * period_ns = (10^9 * (prescaler + 1) * (MAX_PWM_COUNT + 1)) / CLK_RATE + */ + val = NSEC_PER_SEC / pc->clk_rate; + val *= cdata->max_pwm_cnt + 1; + + dev_dbg(dev, "possible periods for clkrate[HZ]:%lu\n", pc->clk_rate); + + for (i = 0; i <= cdata->max_prescale; i++) { + pc->pwm_periods[i] = val * (i + 1); + dev_dbg(dev, "prescale:%d, period[ns]:%lu\n", + i, pc->pwm_periods[i]); + } +} + +static int sti_pwm_cmp_periods(const void *key, const void *elt) +{ + unsigned long i = *(unsigned long *)key; + unsigned long j = *(unsigned long *)elt; + + if (i < j) + return -1; + else + return i == j ? 0 : 1; +} + +/* + * 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 4 bits, so only 16 prescaler values and hence only + * 16 possible period values are supported (for a particular clock rate). + * The requested period will be applied only if it matches one of these + * 16 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 device *dev = pc->dev; + unsigned int prescale, pwmvalx; + unsigned long *found; + int ret; + + /* + * Search for matching period value. The corresponding index is our + * prescale value + */ + found = bsearch(&period_ns, &pc->pwm_periods[0], + cdata->max_prescale + 1, sizeof(unsigned long), + sti_pwm_cmp_periods); + if (!found) { + dev_err(dev, "failed to find matching period\n"); + return -EINVAL; + } + + prescale = found - &pc->pwm_periods[0]; + + /* + * 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; + + dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n", + prescale, period_ns, duty_ns, pwmvalx); + + /* Enable clock before writing to PWM registers */ + ret = clk_enable(pc->clk); + if (ret) + return ret; + + ret = regmap_field_write(pc->prescale, prescale); + if (ret) + goto clk_dis; + + ret = regmap_write(pc->regmap, STI_PWMVAL(pwm->hwpwm), pwmvalx); + if (ret) + goto clk_dis; + + ret = regmap_field_write(pc->pwm_int_en, 0); + +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; + + ret = clk_enable(pc->clk); + if (ret) + return ret; + + ret = regmap_field_write(pc->pwm_en, 1); + if (ret) + dev_err(dev, "%s,pwm_en write failed\n", __func__); + + return ret; +} + +static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) +{ + struct sti_pwm_chip *pc = to_sti_pwmchip(chip); + struct device *dev = pc->dev; + unsigned int val; + + regmap_field_write(pc->pwm_en, 0); + + regmap_read(pc->regmap, STI_CNT, &val); + + dev_dbg(dev, "pwm counter :%u\n", val); + + clk_disable(pc->clk); +} + +static const struct pwm_ops sti_pwm_ops = { + .config = sti_pwm_config, + .enable = sti_pwm_enable, + .disable = sti_pwm_disable, + .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 = devm_regmap_field_alloc(dev, pc->regmap, + reg_fields[PWMCLK_PRESCALE]); + if (IS_ERR(pc->prescale)) + return PTR_ERR(pc->prescale); + + 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; + + ret = sti_pwm_probe_dt(pc); + if (ret) + return ret; + + pc->pwm_periods = devm_kzalloc(dev, + sizeof(unsigned long) * (pc->cdata->max_prescale + 1), + GFP_KERNEL); + if (!pc->pwm_periods) + return -ENOMEM; + + 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; + } + + sti_pwm_calc_periods(pc); + + 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"); |