linux/drivers/counter/stm32-lptimer-cnt.c
Fabrice Gasnier fd5ac974fc counter: stm32-lptimer-cnt: fix the check on arr and cmp registers update
The ARR (auto reload register) and CMP (compare) registers are
successively written. The status bits to check the update of these
registers are polled together with regmap_read_poll_timeout().
The condition to end the loop may become true, even if one of the register
isn't correctly updated.
So ensure both status bits are set before clearing them.

Fixes: d8958824cf ("iio: counter: Add support for STM32 LPTimer")
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20221123133609.465614-1-fabrice.gasnier@foss.st.com/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
2022-11-26 16:49:28 -05:00

524 lines
13 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* STM32 Low-Power Timer Encoder and Counter driver
*
* Copyright (C) STMicroelectronics 2017
*
* Author: Fabrice Gasnier <fabrice.gasnier@st.com>
*
* Inspired by 104-quad-8 and stm32-timer-trigger drivers.
*
*/
#include <linux/bitfield.h>
#include <linux/counter.h>
#include <linux/mfd/stm32-lptimer.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/types.h>
struct stm32_lptim_cnt {
struct device *dev;
struct regmap *regmap;
struct clk *clk;
u32 ceiling;
u32 polarity;
u32 quadrature_mode;
bool enabled;
};
static int stm32_lptim_is_enabled(struct stm32_lptim_cnt *priv)
{
u32 val;
int ret;
ret = regmap_read(priv->regmap, STM32_LPTIM_CR, &val);
if (ret)
return ret;
return FIELD_GET(STM32_LPTIM_ENABLE, val);
}
static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,
int enable)
{
int ret;
u32 val;
val = FIELD_PREP(STM32_LPTIM_ENABLE, enable);
ret = regmap_write(priv->regmap, STM32_LPTIM_CR, val);
if (ret)
return ret;
if (!enable) {
clk_disable(priv->clk);
priv->enabled = false;
return 0;
}
/* LP timer must be enabled before writing CMP & ARR */
ret = regmap_write(priv->regmap, STM32_LPTIM_ARR, priv->ceiling);
if (ret)
return ret;
ret = regmap_write(priv->regmap, STM32_LPTIM_CMP, 0);
if (ret)
return ret;
/* ensure CMP & ARR registers are properly written */
ret = regmap_read_poll_timeout(priv->regmap, STM32_LPTIM_ISR, val,
(val & STM32_LPTIM_CMPOK_ARROK) == STM32_LPTIM_CMPOK_ARROK,
100, 1000);
if (ret)
return ret;
ret = regmap_write(priv->regmap, STM32_LPTIM_ICR,
STM32_LPTIM_CMPOKCF_ARROKCF);
if (ret)
return ret;
ret = clk_enable(priv->clk);
if (ret) {
regmap_write(priv->regmap, STM32_LPTIM_CR, 0);
return ret;
}
priv->enabled = true;
/* Start LP timer in continuous mode */
return regmap_update_bits(priv->regmap, STM32_LPTIM_CR,
STM32_LPTIM_CNTSTRT, STM32_LPTIM_CNTSTRT);
}
static int stm32_lptim_setup(struct stm32_lptim_cnt *priv, int enable)
{
u32 mask = STM32_LPTIM_ENC | STM32_LPTIM_COUNTMODE |
STM32_LPTIM_CKPOL | STM32_LPTIM_PRESC;
u32 val;
/* Setup LP timer encoder/counter and polarity, without prescaler */
if (priv->quadrature_mode)
val = enable ? STM32_LPTIM_ENC : 0;
else
val = enable ? STM32_LPTIM_COUNTMODE : 0;
val |= FIELD_PREP(STM32_LPTIM_CKPOL, enable ? priv->polarity : 0);
return regmap_update_bits(priv->regmap, STM32_LPTIM_CFGR, mask, val);
}
/*
* In non-quadrature mode, device counts up on active edge.
* In quadrature mode, encoder counting scenarios are as follows:
* +---------+----------+--------------------+--------------------+
* | Active | Level on | IN1 signal | IN2 signal |
* | edge | opposite +----------+---------+----------+---------+
* | | signal | Rising | Falling | Rising | Falling |
* +---------+----------+----------+---------+----------+---------+
* | Rising | High -> | Down | - | Up | - |
* | edge | Low -> | Up | - | Down | - |
* +---------+----------+----------+---------+----------+---------+
* | Falling | High -> | - | Up | - | Down |
* | edge | Low -> | - | Down | - | Up |
* +---------+----------+----------+---------+----------+---------+
* | Both | High -> | Down | Up | Up | Down |
* | edges | Low -> | Up | Down | Down | Up |
* +---------+----------+----------+---------+----------+---------+
*/
static const enum counter_function stm32_lptim_cnt_functions[] = {
COUNTER_FUNCTION_INCREASE,
COUNTER_FUNCTION_QUADRATURE_X4,
};
static const enum counter_synapse_action stm32_lptim_cnt_synapse_actions[] = {
COUNTER_SYNAPSE_ACTION_RISING_EDGE,
COUNTER_SYNAPSE_ACTION_FALLING_EDGE,
COUNTER_SYNAPSE_ACTION_BOTH_EDGES,
COUNTER_SYNAPSE_ACTION_NONE,
};
static int stm32_lptim_cnt_read(struct counter_device *counter,
struct counter_count *count, u64 *val)
{
struct stm32_lptim_cnt *const priv = counter_priv(counter);
u32 cnt;
int ret;
ret = regmap_read(priv->regmap, STM32_LPTIM_CNT, &cnt);
if (ret)
return ret;
*val = cnt;
return 0;
}
static int stm32_lptim_cnt_function_read(struct counter_device *counter,
struct counter_count *count,
enum counter_function *function)
{
struct stm32_lptim_cnt *const priv = counter_priv(counter);
if (!priv->quadrature_mode) {
*function = COUNTER_FUNCTION_INCREASE;
return 0;
}
if (priv->polarity == STM32_LPTIM_CKPOL_BOTH_EDGES) {
*function = COUNTER_FUNCTION_QUADRATURE_X4;
return 0;
}
return -EINVAL;
}
static int stm32_lptim_cnt_function_write(struct counter_device *counter,
struct counter_count *count,
enum counter_function function)
{
struct stm32_lptim_cnt *const priv = counter_priv(counter);
if (stm32_lptim_is_enabled(priv))
return -EBUSY;
switch (function) {
case COUNTER_FUNCTION_INCREASE:
priv->quadrature_mode = 0;
return 0;
case COUNTER_FUNCTION_QUADRATURE_X4:
priv->quadrature_mode = 1;
priv->polarity = STM32_LPTIM_CKPOL_BOTH_EDGES;
return 0;
default:
/* should never reach this path */
return -EINVAL;
}
}
static int stm32_lptim_cnt_enable_read(struct counter_device *counter,
struct counter_count *count,
u8 *enable)
{
struct stm32_lptim_cnt *const priv = counter_priv(counter);
int ret;
ret = stm32_lptim_is_enabled(priv);
if (ret < 0)
return ret;
*enable = ret;
return 0;
}
static int stm32_lptim_cnt_enable_write(struct counter_device *counter,
struct counter_count *count,
u8 enable)
{
struct stm32_lptim_cnt *const priv = counter_priv(counter);
int ret;
/* Check nobody uses the timer, or already disabled/enabled */
ret = stm32_lptim_is_enabled(priv);
if ((ret < 0) || (!ret && !enable))
return ret;
if (enable && ret)
return -EBUSY;
ret = stm32_lptim_setup(priv, enable);
if (ret)
return ret;
ret = stm32_lptim_set_enable_state(priv, enable);
if (ret)
return ret;
return 0;
}
static int stm32_lptim_cnt_ceiling_read(struct counter_device *counter,
struct counter_count *count,
u64 *ceiling)
{
struct stm32_lptim_cnt *const priv = counter_priv(counter);
*ceiling = priv->ceiling;
return 0;
}
static int stm32_lptim_cnt_ceiling_write(struct counter_device *counter,
struct counter_count *count,
u64 ceiling)
{
struct stm32_lptim_cnt *const priv = counter_priv(counter);
if (stm32_lptim_is_enabled(priv))
return -EBUSY;
if (ceiling > STM32_LPTIM_MAX_ARR)
return -ERANGE;
priv->ceiling = ceiling;
return 0;
}
static struct counter_comp stm32_lptim_cnt_ext[] = {
COUNTER_COMP_ENABLE(stm32_lptim_cnt_enable_read,
stm32_lptim_cnt_enable_write),
COUNTER_COMP_CEILING(stm32_lptim_cnt_ceiling_read,
stm32_lptim_cnt_ceiling_write),
};
static int stm32_lptim_cnt_action_read(struct counter_device *counter,
struct counter_count *count,
struct counter_synapse *synapse,
enum counter_synapse_action *action)
{
struct stm32_lptim_cnt *const priv = counter_priv(counter);
enum counter_function function;
int err;
err = stm32_lptim_cnt_function_read(counter, count, &function);
if (err)
return err;
switch (function) {
case COUNTER_FUNCTION_INCREASE:
/* LP Timer acts as up-counter on input 1 */
if (synapse->signal->id != count->synapses[0].signal->id) {
*action = COUNTER_SYNAPSE_ACTION_NONE;
return 0;
}
switch (priv->polarity) {
case STM32_LPTIM_CKPOL_RISING_EDGE:
*action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
return 0;
case STM32_LPTIM_CKPOL_FALLING_EDGE:
*action = COUNTER_SYNAPSE_ACTION_FALLING_EDGE;
return 0;
case STM32_LPTIM_CKPOL_BOTH_EDGES:
*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
return 0;
default:
/* should never reach this path */
return -EINVAL;
}
case COUNTER_FUNCTION_QUADRATURE_X4:
*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
return 0;
default:
/* should never reach this path */
return -EINVAL;
}
}
static int stm32_lptim_cnt_action_write(struct counter_device *counter,
struct counter_count *count,
struct counter_synapse *synapse,
enum counter_synapse_action action)
{
struct stm32_lptim_cnt *const priv = counter_priv(counter);
enum counter_function function;
int err;
if (stm32_lptim_is_enabled(priv))
return -EBUSY;
err = stm32_lptim_cnt_function_read(counter, count, &function);
if (err)
return err;
/* only set polarity when in counter mode (on input 1) */
if (function != COUNTER_FUNCTION_INCREASE
|| synapse->signal->id != count->synapses[0].signal->id)
return -EINVAL;
switch (action) {
case COUNTER_SYNAPSE_ACTION_RISING_EDGE:
priv->polarity = STM32_LPTIM_CKPOL_RISING_EDGE;
return 0;
case COUNTER_SYNAPSE_ACTION_FALLING_EDGE:
priv->polarity = STM32_LPTIM_CKPOL_FALLING_EDGE;
return 0;
case COUNTER_SYNAPSE_ACTION_BOTH_EDGES:
priv->polarity = STM32_LPTIM_CKPOL_BOTH_EDGES;
return 0;
default:
return -EINVAL;
}
}
static const struct counter_ops stm32_lptim_cnt_ops = {
.count_read = stm32_lptim_cnt_read,
.function_read = stm32_lptim_cnt_function_read,
.function_write = stm32_lptim_cnt_function_write,
.action_read = stm32_lptim_cnt_action_read,
.action_write = stm32_lptim_cnt_action_write,
};
static struct counter_signal stm32_lptim_cnt_signals[] = {
{
.id = 0,
.name = "Channel 1 Quadrature A"
},
{
.id = 1,
.name = "Channel 1 Quadrature B"
}
};
static struct counter_synapse stm32_lptim_cnt_synapses[] = {
{
.actions_list = stm32_lptim_cnt_synapse_actions,
.num_actions = ARRAY_SIZE(stm32_lptim_cnt_synapse_actions),
.signal = &stm32_lptim_cnt_signals[0]
},
{
.actions_list = stm32_lptim_cnt_synapse_actions,
.num_actions = ARRAY_SIZE(stm32_lptim_cnt_synapse_actions),
.signal = &stm32_lptim_cnt_signals[1]
}
};
/* LP timer with encoder */
static struct counter_count stm32_lptim_enc_counts = {
.id = 0,
.name = "LPTimer Count",
.functions_list = stm32_lptim_cnt_functions,
.num_functions = ARRAY_SIZE(stm32_lptim_cnt_functions),
.synapses = stm32_lptim_cnt_synapses,
.num_synapses = ARRAY_SIZE(stm32_lptim_cnt_synapses),
.ext = stm32_lptim_cnt_ext,
.num_ext = ARRAY_SIZE(stm32_lptim_cnt_ext)
};
/* LP timer without encoder (counter only) */
static struct counter_count stm32_lptim_in1_counts = {
.id = 0,
.name = "LPTimer Count",
.functions_list = stm32_lptim_cnt_functions,
.num_functions = 1,
.synapses = stm32_lptim_cnt_synapses,
.num_synapses = 1,
.ext = stm32_lptim_cnt_ext,
.num_ext = ARRAY_SIZE(stm32_lptim_cnt_ext)
};
static int stm32_lptim_cnt_probe(struct platform_device *pdev)
{
struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent);
struct counter_device *counter;
struct stm32_lptim_cnt *priv;
int ret;
if (IS_ERR_OR_NULL(ddata))
return -EINVAL;
counter = devm_counter_alloc(&pdev->dev, sizeof(*priv));
if (!counter)
return -ENOMEM;
priv = counter_priv(counter);
priv->dev = &pdev->dev;
priv->regmap = ddata->regmap;
priv->clk = ddata->clk;
priv->ceiling = STM32_LPTIM_MAX_ARR;
/* Initialize Counter device */
counter->name = dev_name(&pdev->dev);
counter->parent = &pdev->dev;
counter->ops = &stm32_lptim_cnt_ops;
if (ddata->has_encoder) {
counter->counts = &stm32_lptim_enc_counts;
counter->num_signals = ARRAY_SIZE(stm32_lptim_cnt_signals);
} else {
counter->counts = &stm32_lptim_in1_counts;
counter->num_signals = 1;
}
counter->num_counts = 1;
counter->signals = stm32_lptim_cnt_signals;
platform_set_drvdata(pdev, priv);
ret = devm_counter_add(&pdev->dev, counter);
if (ret < 0)
return dev_err_probe(&pdev->dev, ret, "Failed to add counter\n");
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int stm32_lptim_cnt_suspend(struct device *dev)
{
struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
int ret;
/* Only take care of enabled counter: don't disturb other MFD child */
if (priv->enabled) {
ret = stm32_lptim_setup(priv, 0);
if (ret)
return ret;
ret = stm32_lptim_set_enable_state(priv, 0);
if (ret)
return ret;
/* Force enable state for later resume */
priv->enabled = true;
}
return pinctrl_pm_select_sleep_state(dev);
}
static int stm32_lptim_cnt_resume(struct device *dev)
{
struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
int ret;
ret = pinctrl_pm_select_default_state(dev);
if (ret)
return ret;
if (priv->enabled) {
priv->enabled = false;
ret = stm32_lptim_setup(priv, 1);
if (ret)
return ret;
ret = stm32_lptim_set_enable_state(priv, 1);
if (ret)
return ret;
}
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(stm32_lptim_cnt_pm_ops, stm32_lptim_cnt_suspend,
stm32_lptim_cnt_resume);
static const struct of_device_id stm32_lptim_cnt_of_match[] = {
{ .compatible = "st,stm32-lptimer-counter", },
{},
};
MODULE_DEVICE_TABLE(of, stm32_lptim_cnt_of_match);
static struct platform_driver stm32_lptim_cnt_driver = {
.probe = stm32_lptim_cnt_probe,
.driver = {
.name = "stm32-lptimer-counter",
.of_match_table = stm32_lptim_cnt_of_match,
.pm = &stm32_lptim_cnt_pm_ops,
},
};
module_platform_driver(stm32_lptim_cnt_driver);
MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
MODULE_ALIAS("platform:stm32-lptimer-counter");
MODULE_DESCRIPTION("STMicroelectronics STM32 LPTIM counter driver");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS(COUNTER);