counter: Add STM32 Timer quadrature encoder

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Benjamin Gaignard 2019-04-02 15:30:42 +09:00 committed by Greg Kroah-Hartman
parent 7e798ef90c
commit ad29937e20
3 changed files with 401 additions and 0 deletions

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@ -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

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@ -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

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@ -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");