[PATCH v9 4/8] pwm: add driver for STM32 plaftorm

Benjamin Gaignard
2017-01-20T09:17:58Z

This driver adds support for PWM driver on STM32 platform.
The SoC have multiple instances of the hardware IP and each
of them could have small differences: number of channels,
complementary output, auto reload register size...

version 9:
- fix commit message header
- remove one space MODULE_ALIAS

version 8:
- fix comments done by Thierry on version 7

version 6:
- change st,breakinput parameter to make it usuable for stm32f7 too.

version 4:
- detect at probe time hardware capabilities
- fix comments done on v2 and v3
- use PWM atomic ops

version 2:
- only keep one comptatible
- use DT parameters to discover hardware block configuration

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Acked-by: Thierry Reding <treding@nvidia.com>
---
drivers/pwm/Kconfig | 9 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-stm32.c | 398 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 408 insertions(+)
create mode 100644 drivers/pwm/pwm-stm32.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index f92dd41..2d0cfaa 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -397,6 +397,15 @@ config PWM_STI
To compile this driver as a module, choose M here: the module
will be called pwm-sti.

+config PWM_STM32
+ tristate "STMicroelectronics STM32 PWM"
+ depends on MFD_STM32_TIMERS || COMPILE_TEST
+ help
+ Generic PWM framework driver for STM32 SoCs.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-stm32.
+
config PWM_STMPE
bool "STMPE expander PWM export"
depends on MFD_STMPE
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index a48bdb5..346a83b 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -38,6 +38,7 @@ 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-$(CONFIG_PWM_STM32) += pwm-stm32.o
obj-$(CONFIG_PWM_STMPE) += pwm-stmpe.o
obj-$(CONFIG_PWM_SUN4I) += pwm-sun4i.o
obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o
diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
new file mode 100644
index 0000000..ce6232e
--- /dev/null
+++ b/drivers/pwm/pwm-stm32.c
@@ -0,0 +1,398 @@
+/*
+ * Copyright (C) STMicroelectronics 2016
+ *
+ * Author: Gerald Baeza <gerald.baeza@st.com>
+ *
+ * License terms: GNU General Public License (GPL), version 2
+ *
+ * Inspired by timer-stm32.c from Maxime Coquelin
+ * pwm-atmel.c from Bo Shen
+ */
+
+#include <linux/mfd/stm32-timers.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#define CCMR_CHANNEL_SHIFT 8
+#define CCMR_CHANNEL_MASK 0xFF
+#define MAX_BREAKINPUT 2
+
+struct stm32_pwm {
+ struct pwm_chip chip;
+ struct device *dev;
+ struct clk *clk;
+ struct regmap *regmap;
+ u32 max_arr;
+ bool have_complementary_output;
+};
+
+struct stm32_breakinput {
+ u32 index;
+ u32 level;
+ u32 filter;
+};
+
+static inline struct stm32_pwm *to_stm32_pwm_dev(struct pwm_chip *chip)
+{
+ return container_of(chip, struct stm32_pwm, chip);
+}
+
+static u32 active_channels(struct stm32_pwm *dev)
+{
+ u32 ccer;
+
+ regmap_read(dev->regmap, TIM_CCER, &ccer);
+
+ return ccer & TIM_CCER_CCXE;
+}
+
+static int write_ccrx(struct stm32_pwm *dev, int ch, u32 value)
+{
+ switch (ch) {
+ case 0:
+ return regmap_write(dev->regmap, TIM_CCR1, value);
+ case 1:
+ return regmap_write(dev->regmap, TIM_CCR2, value);
+ case 2:
+ return regmap_write(dev->regmap, TIM_CCR3, value);
+ case 3:
+ return regmap_write(dev->regmap, TIM_CCR4, value);
+ }
+ return -EINVAL;
+}
+
+static int stm32_pwm_config(struct stm32_pwm *priv, int ch,
+ int duty_ns, int period_ns)
+{
+ unsigned long long prd, div, dty;
+ unsigned int prescaler = 0;
+ u32 ccmr, mask, shift;
+
+ /* Period and prescaler values depends on clock rate */
+ div = (unsigned long long)clk_get_rate(priv->clk) * period_ns;
+
+ do_div(div, NSEC_PER_SEC);
+ prd = div;
+
+ while (div > priv->max_arr) {
+ prescaler++;
+ div = prd;
+ do_div(div, prescaler + 1);
+ }
+
+ prd = div;
+
+ if (prescaler > MAX_TIM_PSC)
+ return -EINVAL;
+
+ /*
+ * All channels share the same prescaler and counter so when two
+ * channels are active at the same time we can't change them
+ */
+ if (active_channels(priv) & ~(1 << ch * 4)) {
+ u32 psc, arr;
+
+ regmap_read(priv->regmap, TIM_PSC, &psc);
+ regmap_read(priv->regmap, TIM_ARR, &arr);
+
+ if ((psc != prescaler) || (arr != prd - 1))
+ return -EBUSY;
+ }
+
+ regmap_write(priv->regmap, TIM_PSC, prescaler);
+ regmap_write(priv->regmap, TIM_ARR, prd - 1);
+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
+
+ /* Calculate the duty cycles */
+ dty = prd * duty_ns;
+ do_div(dty, period_ns);
+
+ write_ccrx(priv, ch, dty);
+
+ /* Configure output mode */
+ shift = (ch & 0x1) * CCMR_CHANNEL_SHIFT;
+ ccmr = (TIM_CCMR_PE | TIM_CCMR_M1) << shift;
+ mask = CCMR_CHANNEL_MASK << shift;
+
+ if (ch < 2)
+ regmap_update_bits(priv->regmap, TIM_CCMR1, mask, ccmr);
+ else
+ regmap_update_bits(priv->regmap, TIM_CCMR2, mask, ccmr);
+
+ regmap_update_bits(priv->regmap, TIM_BDTR,
+ TIM_BDTR_MOE | TIM_BDTR_AOE,
+ TIM_BDTR_MOE | TIM_BDTR_AOE);
+
+ return 0;
+}
+
+static int stm32_pwm_set_polarity(struct stm32_pwm *priv, int ch,
+ enum pwm_polarity polarity)
+{
+ u32 mask;
+
+ mask = TIM_CCER_CC1P << (ch * 4);
+ if (priv->have_complementary_output)
+ mask |= TIM_CCER_CC1NP << (ch * 4);
+
+ regmap_update_bits(priv->regmap, TIM_CCER, mask,
+ polarity == PWM_POLARITY_NORMAL ? 0 : mask);
+
+ return 0;
+}
+
+static int stm32_pwm_enable(struct stm32_pwm *priv, int ch)
+{
+ u32 mask;
+ int ret;
+
+ ret = clk_enable(priv->clk);
+ if (ret)
+ return ret;
+
+ /* Enable channel */
+ mask = TIM_CCER_CC1E << (ch * 4);
+ if (priv->have_complementary_output)
+ mask |= TIM_CCER_CC1NE << (ch * 4);
+
+ regmap_update_bits(priv->regmap, TIM_CCER, mask, mask);
+
+ /* Make sure that registers are updated */
+ regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
+
+ /* Enable controller */
+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
+
+ return 0;
+}
+
+static void stm32_pwm_disable(struct stm32_pwm *priv, int ch)
+{
+ u32 mask;
+
+ /* Disable channel */
+ mask = TIM_CCER_CC1E << (ch * 4);
+ if (priv->have_complementary_output)
+ mask |= TIM_CCER_CC1NE << (ch * 4);
+
+ regmap_update_bits(priv->regmap, TIM_CCER, mask, 0);
+
+ /* When all channels are disabled, we can disable the controller */
+ if (!active_channels(priv))
+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
+
+ clk_disable(priv->clk);
+}
+
+static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct pwm_state curstate;
+ bool enabled;
+ struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
+ int ret;
+
+ enabled = pwm->state.enabled;
+
+ if (enabled && !state->enabled) {
+ stm32_pwm_disable(priv, pwm->hwpwm);
+ return 0;
+ }
+
+ if (state->polarity != curstate.polarity)
+ stm32_pwm_set_polarity(priv, pwm->hwpwm, state->polarity);
+
+ ret = stm32_pwm_config(priv, pwm->hwpwm,
+ state->duty_cycle, state->period);
+ if (ret)
+ return ret;
+
+ if (!enabled && state->enabled)
+ ret = stm32_pwm_enable(priv, pwm->hwpwm);
+
+ return ret;
+}
+
+static const struct pwm_ops stm32pwm_ops = {
+ .owner = THIS_MODULE,
+ .apply = stm32_pwm_apply,
+};
+
+static int stm32_pwm_set_breakinput(struct stm32_pwm *priv,
+ int index, int level, int filter)
+{
+ u32 bke = (index == 0) ? TIM_BDTR_BKE : TIM_BDTR_BK2E;
+ int shift = (index == 0) ? TIM_BDTR_BKF_SHIFT : TIM_BDTR_BK2F_SHIFT;
+ u32 mask = (index == 0) ? TIM_BDTR_BKE | TIM_BDTR_BKP | TIM_BDTR_BKF
+ : TIM_BDTR_BK2E | TIM_BDTR_BK2P | TIM_BDTR_BK2F;
+ u32 bdtr = bke;
+
+ /*
+ * The both bits could be set since only one will be wrote
+ * due to mask value.
+ */
+ if (level)
+ bdtr |= TIM_BDTR_BKP | TIM_BDTR_BK2P;
+
+ bdtr |= (filter & TIM_BDTR_BKF_MASK) << shift;
+
+ regmap_update_bits(priv->regmap, TIM_BDTR, mask, bdtr);
+
+ regmap_read(priv->regmap, TIM_BDTR, &bdtr);
+
+ return (bdtr & bke) ? 0 : -EINVAL;
+}
+
+static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
+ struct device_node *np)
+{
+ struct stm32_breakinput breakinput[MAX_BREAKINPUT];
+ int nb, ret, i, array_size;
+
+ nb = of_property_count_elems_of_size(np, "st,breakinput",
+ sizeof(struct stm32_breakinput));
+
+ /*
+ * Because "st,breakinput" parameter is optional do not make probe
+ * failed if it doesn't exist.
+ */
+ if (nb <= 0)
+ return 0;
+
+ if (nb > MAX_BREAKINPUT)
+ return -EINVAL;
+
+ array_size = nb * sizeof(struct stm32_breakinput) / sizeof(u32);
+ ret = of_property_read_u32_array(np, "st,breakinput",
+ (u32 *)breakinput, array_size);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < nb && !ret; i++) {
+ ret = stm32_pwm_set_breakinput(priv,
+ breakinput[i].index,
+ breakinput[i].level,
+ breakinput[i].filter);
+ }
+
+ return ret;
+}
+
+static void stm32_pwm_detect_complementary(struct stm32_pwm *priv)
+{
+ u32 ccer;
+
+ /*
+ * If complementary bit doesn't exist writing 1 will have no
+ * effect so we can detect it.
+ */
+ regmap_update_bits(priv->regmap,
+ TIM_CCER, TIM_CCER_CC1NE, TIM_CCER_CC1NE);
+ regmap_read(priv->regmap, TIM_CCER, &ccer);
+ regmap_update_bits(priv->regmap, TIM_CCER, TIM_CCER_CC1NE, 0);
+
+ priv->have_complementary_output = (ccer != 0);
+}
+
+static int stm32_pwm_detect_channels(struct stm32_pwm *priv)
+{
+ u32 ccer;
+ int npwm = 0;
+
+ /*
+ * If channels enable bits don't exist writing 1 will have no
+ * effect so we can detect and count them.
+ */
+ regmap_update_bits(priv->regmap,
+ TIM_CCER, TIM_CCER_CCXE, TIM_CCER_CCXE);
+ regmap_read(priv->regmap, TIM_CCER, &ccer);
+ regmap_update_bits(priv->regmap, TIM_CCER, TIM_CCER_CCXE, 0);
+
+ if (ccer & TIM_CCER_CC1E)
+ npwm++;
+
+ if (ccer & TIM_CCER_CC2E)
+ npwm++;
+
+ if (ccer & TIM_CCER_CC3E)
+ npwm++;
+
+ if (ccer & TIM_CCER_CC4E)
+ npwm++;
+
+ return npwm;
+}
+
+static int stm32_pwm_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
+ struct stm32_pwm *priv;
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->regmap = ddata->regmap;
+ priv->clk = ddata->clk;
+ priv->max_arr = ddata->max_arr;
+
+ if (!priv->regmap || !priv->clk)
+ return -EINVAL;
+
+ ret = stm32_pwm_apply_breakinputs(priv, np);
+ if (ret)
+ return ret;
+
+ stm32_pwm_detect_complementary(priv);
+
+ priv->chip.base = -1;
+ priv->chip.dev = dev;
+ priv->chip.ops = &stm32pwm_ops;
+ priv->chip.npwm = stm32_pwm_detect_channels(priv);
+
+ ret = pwmchip_add(&priv->chip);
+ if (ret < 0)
+ return ret;
+
+ platform_set_drvdata(pdev, priv);
+
+ return 0;
+}
+
+static int stm32_pwm_remove(struct platform_device *pdev)
+{
+ struct stm32_pwm *priv = platform_get_drvdata(pdev);
+ unsigned int i;
+
+ for (i = 0; i < priv->chip.npwm; i++)
+ pwm_disable(&priv->chip.pwms[i]);
+
+ pwmchip_remove(&priv->chip);
+
+ return 0;
+}
+
+static const struct of_device_id stm32_pwm_of_match[] = {
+ { .compatible = "st,stm32-pwm", },
+ { /* end node */ },
+};
+MODULE_DEVICE_TABLE(of, stm32_pwm_of_match);
+
+static struct platform_driver stm32_pwm_driver = {
+ .probe = stm32_pwm_probe,
+ .remove = stm32_pwm_remove,
+ .driver = {
+ .name = "stm32-pwm",
+ .of_match_table = stm32_pwm_of_match,
+ },
+};
+module_platform_driver(stm32_pwm_driver);
+
+MODULE_ALIAS("platform:stm32-pwm");
+MODULE_DESCRIPTION("STMicroelectronics STM32 PWM driver");
+MODULE_LICENSE("GPL v2");
--
1.9.1