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Subject[PATCH v5 8/8] Counter: Add STM32 Timer quadrature encoder
Date
From: Benjamin Gaignard <benjamin.gaignard@st.com>

Implement counter part of the STM32 timer hardware block
by using counter API.
Hardware only support X2 and X4 quadrature modes.
A Preset value can to set to define the maximum value
reachable by the counter.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
---
drivers/counter/Kconfig | 10 ++
drivers/counter/Makefile | 1 +
drivers/counter/stm32-timer-cnt.c | 356 ++++++++++++++++++++++++++++++++++++++
3 files changed, 367 insertions(+)
create mode 100644 drivers/counter/stm32-timer-cnt.c

diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
index 0b28d3ff524b..d758279081ac 100644
--- a/drivers/counter/Kconfig
+++ b/drivers/counter/Kconfig
@@ -35,6 +35,16 @@ config 104_QUAD_8
The base port addresses for the devices may be configured via the base
array module parameter.

+config STM32_TIMER_CNT
+ tristate "STM32 Timer encoder counter driver"
+ depends on MFD_STM32_TIMERS || COMPILE_TEST
+ help
+ Select this option to enable STM32 Timer quadrature encoder
+ and counter driver.
+
+ To compile this driver as a module, choose M here: the
+ module will be called stm32-timer-cnt.
+
config STM32_LPTIMER_CNT
tristate "STM32 LP Timer encoder counter driver"
depends on (MFD_STM32_LPTIMER || COMPILE_TEST) && IIO
diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile
index d721a40aa4a2..9c037d7d1ed6 100644
--- a/drivers/counter/Makefile
+++ b/drivers/counter/Makefile
@@ -8,4 +8,5 @@ obj-$(CONFIG_COUNTER) += counter.o
counter-y := generic-counter.o

obj-$(CONFIG_104_QUAD_8) += 104-quad-8.o
+obj-$(CONFIG_STM32_TIMER_CNT) += stm32-timer-cnt.o
obj-$(CONFIG_STM32_LPTIMER_CNT) += stm32-lptimer-cnt.o
diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
new file mode 100644
index 000000000000..14085615e880
--- /dev/null
+++ b/drivers/counter/stm32-timer-cnt.c
@@ -0,0 +1,356 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * STM32 Timer Encoder and Counter driver
+ *
+ * Copyright (C) STMicroelectronics 2018
+ *
+ * Author: Benjamin Gaignard <benjamin.gaignard@st.com>
+ *
+ */
+#include <linux/counter.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+#include <linux/mfd/stm32-timers.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define TIM_CCMR_CCXS (BIT(8) | BIT(0))
+#define TIM_CCMR_MASK (TIM_CCMR_CC1S | TIM_CCMR_CC2S | \
+ TIM_CCMR_IC1F | TIM_CCMR_IC2F)
+#define TIM_CCER_MASK (TIM_CCER_CC1P | TIM_CCER_CC1NP | \
+ TIM_CCER_CC2P | TIM_CCER_CC2NP)
+
+struct stm32_timer_cnt {
+ struct counter_device counter;
+ struct regmap *regmap;
+ struct clk *clk;
+ u32 preset;
+};
+
+enum stm32_count_function {
+ STM32_COUNT_FUNCTION_QUADRATURE_X2,
+ STM32_COUNT_FUNCTION_QUADRATURE_X4,
+};
+
+static enum count_function stm32_count_functions[] = {
+ [STM32_COUNT_FUNCTION_QUADRATURE_X2] = COUNT_FUNCTION_QUADRATURE_X2,
+ [STM32_COUNT_FUNCTION_QUADRATURE_X4] = COUNT_FUNCTION_QUADRATURE_X4
+};
+
+static int stm32_count_read(struct counter_device *counter,
+ struct counter_count *count,
+ struct count_read_value *val)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ u32 cnt;
+
+ regmap_read(priv->regmap, TIM_CNT, &cnt);
+ set_count_read_value(val, COUNT_POSITION_UNSIGNED, &cnt);
+
+ return 0;
+}
+
+static int stm32_count_write(struct counter_device *counter,
+ struct counter_count *count,
+ struct count_write_value *val)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ u32 cnt;
+ int err;
+
+ err = get_count_write_value(&cnt, COUNT_POSITION_UNSIGNED, val);
+ if (err)
+ return err;
+
+ if (cnt > priv->preset)
+ return -EINVAL;
+
+ return regmap_write(priv->regmap, TIM_CNT, cnt);
+}
+
+static int stm32_count_function_get(struct counter_device *counter,
+ struct counter_count *count,
+ size_t *function)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ u32 smcr;
+
+ regmap_read(priv->regmap, TIM_SMCR, &smcr);
+
+ switch (smcr & TIM_SMCR_SMS) {
+ case 1:
+ *function = STM32_COUNT_FUNCTION_QUADRATURE_X2;
+ return 0;
+ case 3:
+ *function = STM32_COUNT_FUNCTION_QUADRATURE_X4;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static int stm32_count_function_set(struct counter_device *counter,
+ struct counter_count *count,
+ size_t function)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ u32 cr1, sms;
+
+ switch (function) {
+ case STM32_COUNT_FUNCTION_QUADRATURE_X2:
+ sms = 1;
+ break;
+ case STM32_COUNT_FUNCTION_QUADRATURE_X4:
+ sms = 3;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /* Store enable status */
+ regmap_read(priv->regmap, TIM_CR1, &cr1);
+
+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
+
+ /* TIMx_ARR register shouldn't be buffered (ARPE=0) */
+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, 0);
+ regmap_write(priv->regmap, TIM_ARR, priv->preset);
+
+ regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_SMS, sms);
+
+ /* Make sure that registers are updated */
+ regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
+
+ /* Restore the enable status */
+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, cr1);
+
+ return 0;
+}
+
+static ssize_t stm32_count_direction_read(struct counter_device *counter,
+ struct counter_count *count,
+ void *private, char *buf)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ const char *direction;
+ u32 cr1;
+
+ regmap_read(priv->regmap, TIM_CR1, &cr1);
+ direction = (cr1 & TIM_CR1_DIR) ? "backward" : "forward";
+
+ return scnprintf(buf, PAGE_SIZE, "%s\n", direction);
+}
+
+static ssize_t stm32_count_preset_read(struct counter_device *counter,
+ struct counter_count *count,
+ void *private, char *buf)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ u32 arr;
+
+ regmap_read(priv->regmap, TIM_ARR, &arr);
+
+ return snprintf(buf, PAGE_SIZE, "%u\n", arr);
+}
+
+static ssize_t stm32_count_preset_write(struct counter_device *counter,
+ struct counter_count *count,
+ void *private,
+ const char *buf, size_t len)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ unsigned int preset;
+ int ret;
+
+ ret = kstrtouint(buf, 0, &preset);
+ if (ret)
+ return ret;
+
+ /* TIMx_ARR register shouldn't be buffered (ARPE=0) */
+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, 0);
+ regmap_write(priv->regmap, TIM_ARR, preset);
+
+ priv->preset = preset;
+ return len;
+}
+
+static ssize_t stm32_count_enable_read(struct counter_device *counter,
+ struct counter_count *count,
+ void *private, char *buf)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ u32 cr1;
+
+ regmap_read(priv->regmap, TIM_CR1, &cr1);
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)(cr1 & TIM_CR1_CEN));
+}
+
+static ssize_t stm32_count_enable_write(struct counter_device *counter,
+ struct counter_count *count,
+ void *private,
+ const char *buf, size_t len)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ int err;
+ u32 cr1;
+ bool enable;
+
+ err = kstrtobool(buf, &enable);
+ if (err)
+ return err;
+
+ if (enable) {
+ regmap_read(priv->regmap, TIM_CR1, &cr1);
+ if (!(cr1 & TIM_CR1_CEN))
+ clk_enable(priv->clk);
+
+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN,
+ TIM_CR1_CEN);
+ } else {
+ regmap_read(priv->regmap, TIM_CR1, &cr1);
+ regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
+ if (cr1 & TIM_CR1_CEN)
+ clk_disable(priv->clk);
+ }
+
+ return len;
+}
+
+static const struct counter_count_ext stm32_count_ext[] = {
+ {
+ .name = "direction",
+ .read = stm32_count_direction_read,
+ },
+ {
+ .name = "enable",
+ .read = stm32_count_enable_read,
+ .write = stm32_count_enable_write
+ },
+ {
+ .name = "preset",
+ .read = stm32_count_preset_read,
+ .write = stm32_count_preset_write
+ },
+};
+
+enum stm32_synapse_action {
+ STM32_SYNAPSE_ACTION_RISING_EDGE = 0,
+ STM32_SYNAPSE_ACTION_BOTH_EDGES
+};
+
+static enum synapse_action stm32_synapse_actions[] = {
+ [STM32_SYNAPSE_ACTION_RISING_EDGE] = SYNAPSE_ACTION_RISING_EDGE,
+ [STM32_SYNAPSE_ACTION_BOTH_EDGES] = SYNAPSE_ACTION_BOTH_EDGES
+};
+
+static int stm32_action_get(struct counter_device *counter,
+ struct counter_count *count,
+ struct counter_synapse *synapse,
+ size_t *action)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ u32 smcr;
+
+ regmap_read(priv->regmap, TIM_SMCR, &smcr);
+
+ switch (smcr & TIM_SMCR_SMS) {
+ case 1:
+ *action = STM32_SYNAPSE_ACTION_RISING_EDGE;
+ return 0;
+ case 3:
+ *action = STM32_SYNAPSE_ACTION_BOTH_EDGES;
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static struct counter_signal stm32_signals[] = {
+ {
+ .id = 0,
+ .name = "Channel 1 Quadrature A"
+ },
+ {
+ .id = 1,
+ .name = "Channel 1 Quadrature B"
+ }
+};
+
+static struct counter_synapse stm32_count_synapses[] = {
+ {
+ .actions_list = stm32_synapse_actions,
+ .num_actions = ARRAY_SIZE(stm32_synapse_actions),
+ .signal = &stm32_signals[0]
+ },
+ {
+ .actions_list = stm32_synapse_actions,
+ .num_actions = ARRAY_SIZE(stm32_synapse_actions),
+ .signal = &stm32_signals[1]
+ }
+};
+
+static struct counter_count stm32_counts = {
+ .id = 0,
+ .name = "Channel 1 Count",
+ .functions_list = stm32_count_functions,
+ .num_functions = ARRAY_SIZE(stm32_count_functions),
+ .synapses = stm32_count_synapses,
+ .num_synapses = ARRAY_SIZE(stm32_count_synapses),
+ .ext = stm32_count_ext,
+ .num_ext = ARRAY_SIZE(stm32_count_ext)
+};
+
+static int stm32_timer_cnt_probe(struct platform_device *pdev)
+{
+ struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
+ struct device *dev = &pdev->dev;
+ struct stm32_timer_cnt *priv;
+
+ if (IS_ERR_OR_NULL(ddata))
+ return -EINVAL;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->regmap = ddata->regmap;
+ priv->clk = ddata->clk;
+ priv->preset = ddata->max_arr;
+
+ priv->counter.name = dev_name(dev);
+ priv->counter.parent = dev;
+ priv->counter.count_read = stm32_count_read;
+ priv->counter.count_write = stm32_count_write;
+ priv->counter.function_get = stm32_count_function_get;
+ priv->counter.function_set = stm32_count_function_set;
+ priv->counter.action_get = stm32_action_get;
+ priv->counter.counts = &stm32_counts;
+ priv->counter.num_counts = 1;
+ priv->counter.signals = stm32_signals;
+ priv->counter.num_signals = ARRAY_SIZE(stm32_signals);
+ priv->counter.priv = priv;
+
+ /* Register Counter device */
+ return devm_counter_register(dev, &priv->counter);
+}
+
+static const struct of_device_id stm32_timer_cnt_of_match[] = {
+ { .compatible = "st,stm32-timer-counter", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, stm32_timer_cnt_of_match);
+
+static struct platform_driver stm32_timer_cnt_driver = {
+ .probe = stm32_timer_cnt_probe,
+ .driver = {
+ .name = "stm32-timer-counter",
+ .of_match_table = stm32_timer_cnt_of_match,
+ },
+};
+module_platform_driver(stm32_timer_cnt_driver);
+
+MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@st.com>");
+MODULE_ALIAS("platform:stm32-timer-counter");
+MODULE_DESCRIPTION("STMicroelectronics STM32 TIMER counter driver");
+MODULE_LICENSE("GPL v2");
--
2.16.2
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