linux-stable/drivers/mfd/stm32-timers.c
Peter Ujfalusi 8d7de07783 mfd: stm32-timers: Use dma_request_chan() instead dma_request_slave_channel()
dma_request_slave_channel() is a wrapper on top of dma_request_chan()
eating up the error code.

By using dma_request_chan() directly the driver can support deferred
probing against DMA.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2020-05-26 10:51:20 +01:00

289 lines
7.6 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) STMicroelectronics 2016
* Author: Benjamin Gaignard <benjamin.gaignard@st.com>
*/
#include <linux/bitfield.h>
#include <linux/mfd/stm32-timers.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/reset.h>
#define STM32_TIMERS_MAX_REGISTERS 0x3fc
/* DIER register DMA enable bits */
static const u32 stm32_timers_dier_dmaen[STM32_TIMERS_MAX_DMAS] = {
TIM_DIER_CC1DE,
TIM_DIER_CC2DE,
TIM_DIER_CC3DE,
TIM_DIER_CC4DE,
TIM_DIER_UIE,
TIM_DIER_TDE,
TIM_DIER_COMDE
};
static void stm32_timers_dma_done(void *p)
{
struct stm32_timers_dma *dma = p;
struct dma_tx_state state;
enum dma_status status;
status = dmaengine_tx_status(dma->chan, dma->chan->cookie, &state);
if (status == DMA_COMPLETE)
complete(&dma->completion);
}
/**
* stm32_timers_dma_burst_read - Read from timers registers using DMA.
*
* Read from STM32 timers registers using DMA on a single event.
* @dev: reference to stm32_timers MFD device
* @buf: DMA'able destination buffer
* @id: stm32_timers_dmas event identifier (ch[1..4], up, trig or com)
* @reg: registers start offset for DMA to read from (like CCRx for capture)
* @num_reg: number of registers to read upon each DMA request, starting @reg.
* @bursts: number of bursts to read (e.g. like two for pwm period capture)
* @tmo_ms: timeout (milliseconds)
*/
int stm32_timers_dma_burst_read(struct device *dev, u32 *buf,
enum stm32_timers_dmas id, u32 reg,
unsigned int num_reg, unsigned int bursts,
unsigned long tmo_ms)
{
struct stm32_timers *ddata = dev_get_drvdata(dev);
unsigned long timeout = msecs_to_jiffies(tmo_ms);
struct regmap *regmap = ddata->regmap;
struct stm32_timers_dma *dma = &ddata->dma;
size_t len = num_reg * bursts * sizeof(u32);
struct dma_async_tx_descriptor *desc;
struct dma_slave_config config;
dma_cookie_t cookie;
dma_addr_t dma_buf;
u32 dbl, dba;
long err;
int ret;
/* Sanity check */
if (id < STM32_TIMERS_DMA_CH1 || id >= STM32_TIMERS_MAX_DMAS)
return -EINVAL;
if (!num_reg || !bursts || reg > STM32_TIMERS_MAX_REGISTERS ||
(reg + num_reg * sizeof(u32)) > STM32_TIMERS_MAX_REGISTERS)
return -EINVAL;
if (!dma->chans[id])
return -ENODEV;
mutex_lock(&dma->lock);
/* Select DMA channel in use */
dma->chan = dma->chans[id];
dma_buf = dma_map_single(dev, buf, len, DMA_FROM_DEVICE);
if (dma_mapping_error(dev, dma_buf)) {
ret = -ENOMEM;
goto unlock;
}
/* Prepare DMA read from timer registers, using DMA burst mode */
memset(&config, 0, sizeof(config));
config.src_addr = (dma_addr_t)dma->phys_base + TIM_DMAR;
config.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
ret = dmaengine_slave_config(dma->chan, &config);
if (ret)
goto unmap;
desc = dmaengine_prep_slave_single(dma->chan, dma_buf, len,
DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
if (!desc) {
ret = -EBUSY;
goto unmap;
}
desc->callback = stm32_timers_dma_done;
desc->callback_param = dma;
cookie = dmaengine_submit(desc);
ret = dma_submit_error(cookie);
if (ret)
goto dma_term;
reinit_completion(&dma->completion);
dma_async_issue_pending(dma->chan);
/* Setup and enable timer DMA burst mode */
dbl = FIELD_PREP(TIM_DCR_DBL, bursts - 1);
dba = FIELD_PREP(TIM_DCR_DBA, reg >> 2);
ret = regmap_write(regmap, TIM_DCR, dbl | dba);
if (ret)
goto dma_term;
/* Clear pending flags before enabling DMA request */
ret = regmap_write(regmap, TIM_SR, 0);
if (ret)
goto dcr_clr;
ret = regmap_update_bits(regmap, TIM_DIER, stm32_timers_dier_dmaen[id],
stm32_timers_dier_dmaen[id]);
if (ret)
goto dcr_clr;
err = wait_for_completion_interruptible_timeout(&dma->completion,
timeout);
if (err == 0)
ret = -ETIMEDOUT;
else if (err < 0)
ret = err;
regmap_update_bits(regmap, TIM_DIER, stm32_timers_dier_dmaen[id], 0);
regmap_write(regmap, TIM_SR, 0);
dcr_clr:
regmap_write(regmap, TIM_DCR, 0);
dma_term:
dmaengine_terminate_all(dma->chan);
unmap:
dma_unmap_single(dev, dma_buf, len, DMA_FROM_DEVICE);
unlock:
dma->chan = NULL;
mutex_unlock(&dma->lock);
return ret;
}
EXPORT_SYMBOL_GPL(stm32_timers_dma_burst_read);
static const struct regmap_config stm32_timers_regmap_cfg = {
.reg_bits = 32,
.val_bits = 32,
.reg_stride = sizeof(u32),
.max_register = STM32_TIMERS_MAX_REGISTERS,
};
static void stm32_timers_get_arr_size(struct stm32_timers *ddata)
{
/*
* Only the available bits will be written so when readback
* we get the maximum value of auto reload register
*/
regmap_write(ddata->regmap, TIM_ARR, ~0L);
regmap_read(ddata->regmap, TIM_ARR, &ddata->max_arr);
regmap_write(ddata->regmap, TIM_ARR, 0x0);
}
static int stm32_timers_dma_probe(struct device *dev,
struct stm32_timers *ddata)
{
int i;
int ret = 0;
char name[4];
init_completion(&ddata->dma.completion);
mutex_init(&ddata->dma.lock);
/* Optional DMA support: get valid DMA channel(s) or NULL */
for (i = STM32_TIMERS_DMA_CH1; i <= STM32_TIMERS_DMA_CH4; i++) {
snprintf(name, ARRAY_SIZE(name), "ch%1d", i + 1);
ddata->dma.chans[i] = dma_request_chan(dev, name);
}
ddata->dma.chans[STM32_TIMERS_DMA_UP] = dma_request_chan(dev, "up");
ddata->dma.chans[STM32_TIMERS_DMA_TRIG] = dma_request_chan(dev, "trig");
ddata->dma.chans[STM32_TIMERS_DMA_COM] = dma_request_chan(dev, "com");
for (i = STM32_TIMERS_DMA_CH1; i < STM32_TIMERS_MAX_DMAS; i++) {
if (IS_ERR(ddata->dma.chans[i])) {
/* Save the first error code to return */
if (PTR_ERR(ddata->dma.chans[i]) != -ENODEV && !ret)
ret = PTR_ERR(ddata->dma.chans[i]);
ddata->dma.chans[i] = NULL;
}
}
return ret;
}
static void stm32_timers_dma_remove(struct device *dev,
struct stm32_timers *ddata)
{
int i;
for (i = STM32_TIMERS_DMA_CH1; i < STM32_TIMERS_MAX_DMAS; i++)
if (ddata->dma.chans[i])
dma_release_channel(ddata->dma.chans[i]);
}
static int stm32_timers_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct stm32_timers *ddata;
struct resource *res;
void __iomem *mmio;
int ret;
ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
if (!ddata)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
mmio = devm_ioremap_resource(dev, res);
if (IS_ERR(mmio))
return PTR_ERR(mmio);
/* Timer physical addr for DMA */
ddata->dma.phys_base = res->start;
ddata->regmap = devm_regmap_init_mmio_clk(dev, "int", mmio,
&stm32_timers_regmap_cfg);
if (IS_ERR(ddata->regmap))
return PTR_ERR(ddata->regmap);
ddata->clk = devm_clk_get(dev, NULL);
if (IS_ERR(ddata->clk))
return PTR_ERR(ddata->clk);
stm32_timers_get_arr_size(ddata);
ret = stm32_timers_dma_probe(dev, ddata);
if (ret) {
stm32_timers_dma_remove(dev, ddata);
return ret;
}
platform_set_drvdata(pdev, ddata);
ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
if (ret)
stm32_timers_dma_remove(dev, ddata);
return ret;
}
static int stm32_timers_remove(struct platform_device *pdev)
{
struct stm32_timers *ddata = platform_get_drvdata(pdev);
/*
* Don't use devm_ here: enfore of_platform_depopulate() happens before
* DMA are released, to avoid race on DMA.
*/
of_platform_depopulate(&pdev->dev);
stm32_timers_dma_remove(&pdev->dev, ddata);
return 0;
}
static const struct of_device_id stm32_timers_of_match[] = {
{ .compatible = "st,stm32-timers", },
{ /* end node */ },
};
MODULE_DEVICE_TABLE(of, stm32_timers_of_match);
static struct platform_driver stm32_timers_driver = {
.probe = stm32_timers_probe,
.remove = stm32_timers_remove,
.driver = {
.name = "stm32-timers",
.of_match_table = stm32_timers_of_match,
},
};
module_platform_driver(stm32_timers_driver);
MODULE_DESCRIPTION("STMicroelectronics STM32 Timers");
MODULE_LICENSE("GPL v2");