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SubjectRe: [PATCH v5 8/8] Counter: Add STM32 Timer quadrature encoder
On Fri,  9 Mar 2018 13:43:55 -0500
William Breathitt Gray <vilhelm.gray@gmail.com> wrote:

> 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>
Looks good to me.
The only changes I would make are around things I've suggested for the core.

Nice little driver :)

Jonathan

> ---
> 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");

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