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Subject[PATCH v10 07/18] 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 supports X2 and X4 quadrature modes. A
ceiling value can be set to define the maximum value reachable by the
counter.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
Co-authored-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.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 | 390 ++++++++++++++++++++++++++++++
3 files changed, 401 insertions(+)
create mode 100644 drivers/counter/stm32-timer-cnt.c

diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
index dd3add729529..0bb2340d6087 100644
--- a/drivers/counter/Kconfig
+++ b/drivers/counter/Kconfig
@@ -28,4 +28,14 @@ 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.
+
endif # COUNTER
diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile
index aee0d2ddcf2c..6b4a5be21b00 100644
--- a/drivers/counter/Makefile
+++ b/drivers/counter/Makefile
@@ -5,3 +5,4 @@
obj-$(CONFIG_COUNTER) += counter.o

obj-$(CONFIG_104_QUAD_8) += 104-quad-8.o
+obj-$(CONFIG_STM32_TIMER_CNT) += stm32-timer-cnt.o
diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
new file mode 100644
index 000000000000..644ba18a72ad
--- /dev/null
+++ b/drivers/counter/stm32-timer-cnt.c
@@ -0,0 +1,390 @@
+// 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 ceiling;
+};
+
+/**
+ * stm32_count_function - enumerates stm32 timer counter encoder modes
+ * @STM32_COUNT_SLAVE_MODE_DISABLED: counts on internal clock when CEN=1
+ * @STM32_COUNT_ENCODER_MODE_1: counts TI1FP1 edges, depending on TI2FP2 level
+ * @STM32_COUNT_ENCODER_MODE_2: counts TI2FP2 edges, depending on TI1FP1 level
+ * @STM32_COUNT_ENCODER_MODE_3: counts on both TI1FP1 and TI2FP2 edges
+ */
+enum stm32_count_function {
+ STM32_COUNT_SLAVE_MODE_DISABLED = -1,
+ STM32_COUNT_ENCODER_MODE_1,
+ STM32_COUNT_ENCODER_MODE_2,
+ STM32_COUNT_ENCODER_MODE_3,
+};
+
+static enum counter_count_function stm32_count_functions[] = {
+ [STM32_COUNT_ENCODER_MODE_1] = COUNTER_COUNT_FUNCTION_QUADRATURE_X2_A,
+ [STM32_COUNT_ENCODER_MODE_2] = COUNTER_COUNT_FUNCTION_QUADRATURE_X2_B,
+ [STM32_COUNT_ENCODER_MODE_3] = COUNTER_COUNT_FUNCTION_QUADRATURE_X4,
+};
+
+static int stm32_count_read(struct counter_device *counter,
+ struct counter_count *count,
+ struct counter_count_read_value *val)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ u32 cnt;
+
+ regmap_read(priv->regmap, TIM_CNT, &cnt);
+ counter_count_read_value_set(val, COUNTER_COUNT_POSITION, &cnt);
+
+ return 0;
+}
+
+static int stm32_count_write(struct counter_device *counter,
+ struct counter_count *count,
+ struct counter_count_write_value *val)
+{
+ struct stm32_timer_cnt *const priv = counter->priv;
+ u32 cnt;
+ int err;
+
+ err = counter_count_write_value_get(&cnt, COUNTER_COUNT_POSITION, val);
+ if (err)
+ return err;
+
+ if (cnt > priv->ceiling)
+ 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_ENCODER_MODE_1;
+ return 0;
+ case 2:
+ *function = STM32_COUNT_ENCODER_MODE_2;
+ return 0;
+ case 3:
+ *function = STM32_COUNT_ENCODER_MODE_3;
+ 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_ENCODER_MODE_1:
+ sms = 1;
+ break;
+ case STM32_COUNT_ENCODER_MODE_2:
+ sms = 2;
+ break;
+ case STM32_COUNT_ENCODER_MODE_3:
+ sms = 3;
+ break;
+ default:
+ sms = 0;
+ break;
+ }
+
+ /* 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->ceiling);
+
+ 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_ceiling_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_ceiling_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 ceiling;
+ int ret;
+
+ ret = kstrtouint(buf, 0, &ceiling);
+ 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, ceiling);
+
+ priv->ceiling = ceiling;
+ 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 = "ceiling",
+ .read = stm32_count_ceiling_read,
+ .write = stm32_count_ceiling_write
+ },
+};
+
+enum stm32_synapse_action {
+ STM32_SYNAPSE_ACTION_NONE,
+ STM32_SYNAPSE_ACTION_BOTH_EDGES
+};
+
+static enum counter_synapse_action stm32_synapse_actions[] = {
+ [STM32_SYNAPSE_ACTION_NONE] = COUNTER_SYNAPSE_ACTION_NONE,
+ [STM32_SYNAPSE_ACTION_BOTH_EDGES] = COUNTER_SYNAPSE_ACTION_BOTH_EDGES
+};
+
+static int stm32_action_get(struct counter_device *counter,
+ struct counter_count *count,
+ struct counter_synapse *synapse,
+ size_t *action)
+{
+ size_t function;
+ int err;
+
+ /* Default action mode (e.g. STM32_COUNT_SLAVE_MODE_DISABLED) */
+ *action = STM32_SYNAPSE_ACTION_NONE;
+
+ err = stm32_count_function_get(counter, count, &function);
+ if (err)
+ return 0;
+
+ switch (function) {
+ case STM32_COUNT_ENCODER_MODE_1:
+ /* counts up/down on TI1FP1 edge depending on TI2FP2 level */
+ if (synapse->signal->id == count->synapses[0].signal->id)
+ *action = STM32_SYNAPSE_ACTION_BOTH_EDGES;
+ break;
+ case STM32_COUNT_ENCODER_MODE_2:
+ /* counts up/down on TI2FP2 edge depending on TI1FP1 level */
+ if (synapse->signal->id == count->synapses[1].signal->id)
+ *action = STM32_SYNAPSE_ACTION_BOTH_EDGES;
+ break;
+ case STM32_COUNT_ENCODER_MODE_3:
+ /* counts up/down on both TI1FP1 and TI2FP2 edges */
+ *action = STM32_SYNAPSE_ACTION_BOTH_EDGES;
+ break;
+ }
+
+ return 0;
+}
+
+static const struct counter_ops stm32_timer_cnt_ops = {
+ .count_read = stm32_count_read,
+ .count_write = stm32_count_write,
+ .function_get = stm32_count_function_get,
+ .function_set = stm32_count_function_set,
+ .action_get = stm32_action_get,
+};
+
+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->ceiling = ddata->max_arr;
+
+ priv->counter.name = dev_name(dev);
+ priv->counter.parent = dev;
+ priv->counter.ops = &stm32_timer_cnt_ops;
+ 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");
--
2.21.0
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