Re: [PATCH 4/8] mfd: stm32-timers: add support for dmas

Lee Jones
2018-01-23T13:32:34Z

On Tue, 16 Jan 2018, Fabrice Gasnier wrote:

> STM32 Timers can support up to 7 dma requests:
> 4 channels, update, compare and trigger.
> Optionally request part, or all dmas from stm32-timers MFD core.
> Also, keep reference of device's bus address to allow child drivers to
> transfer data from/to device by using dma.
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier-qxv4g6HH51o@public.gmane.org>
> ---
> drivers/mfd/stm32-timers.c | 37 ++++++++++++++++++++++++++++++++++++-
> include/linux/mfd/stm32-timers.h | 14 ++++++++++++++
> 2 files changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mfd/stm32-timers.c b/drivers/mfd/stm32-timers.c
> index a6675a4..372b51e 100644
> --- a/drivers/mfd/stm32-timers.c
> +++ b/drivers/mfd/stm32-timers.c
> @@ -29,6 +29,23 @@ static void stm32_timers_get_arr_size(struct stm32_timers *ddata)
> regmap_write(ddata->regmap, TIM_ARR, 0x0);
> }
>
> +static void stm32_timers_dma_probe(struct device *dev,
> + struct stm32_timers *ddata)
> +{
> + int i;
> + char name[4];
> +
> + for (i = STM32_TIMERS_DMA_CH1; i <= STM32_TIMERS_DMA_CH4; i++) {
> + snprintf(name, ARRAY_SIZE(name), "ch%1d", i + 1);
> + ddata->dmas[i] = dma_request_slave_channel(dev, name);

And if any of them fail?

> + }
> + ddata->dmas[STM32_TIMERS_DMA_UP] = dma_request_slave_channel(dev, "up");
> + ddata->dmas[STM32_TIMERS_DMA_TRIG] =
> + dma_request_slave_channel(dev, "trig");
> + ddata->dmas[STM32_TIMERS_DMA_COM] =
> + dma_request_slave_channel(dev, "com");

Can you format these in the same why. This hurts my eyes.

> +}
> +
> static int stm32_timers_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -44,6 +61,7 @@ static int stm32_timers_probe(struct platform_device *pdev)
> mmio = devm_ioremap_resource(dev, res);
> if (IS_ERR(mmio))
> return PTR_ERR(mmio);
> + ddata->phys_base = res->start;

What do you use this for?

> ddata->regmap = devm_regmap_init_mmio_clk(dev, "int", mmio,
> &stm32_timers_regmap_cfg);
> @@ -56,9 +74,25 @@ static int stm32_timers_probe(struct platform_device *pdev)
>
> stm32_timers_get_arr_size(ddata);
>
> + stm32_timers_dma_probe(dev, ddata);
> +

Surely this can fail?

> platform_set_drvdata(pdev, ddata);
>
> - return devm_of_platform_populate(&pdev->dev);
> + return of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
> +}
> +
> +static int stm32_timers_remove(struct platform_device *pdev)
> +{
> + struct stm32_timers *ddata = platform_get_drvdata(pdev);
> + int i;
> +
> + of_platform_depopulate(&pdev->dev);
> +
> + for (i = 0; i < STM32_TIMERS_MAX_DMAS; i++)
> + if (ddata->dmas[i])
> + dma_release_channel(ddata->dmas[i]);
> +
> + return 0;
> }
>
> static const struct of_device_id stm32_timers_of_match[] = {
> @@ -69,6 +103,7 @@ static int stm32_timers_probe(struct platform_device *pdev)
>
> 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,
> diff --git a/include/linux/mfd/stm32-timers.h b/include/linux/mfd/stm32-timers.h
> index ce7346e..2b4ffb9 100644
> --- a/include/linux/mfd/stm32-timers.h
> +++ b/include/linux/mfd/stm32-timers.h
> @@ -10,6 +10,7 @@
> #define _LINUX_STM32_GPTIMER_H_
>
> #include <linux/clk.h>
> +#include <linux/dmaengine.h>
> #include <linux/regmap.h>
>
> #define TIM_CR1 0x00 /* Control Register 1 */
> @@ -67,9 +68,22 @@
> #define TIM_BDTR_BKF_SHIFT 16
> #define TIM_BDTR_BK2F_SHIFT 20
>
> +enum stm32_timers_dmas {
> + STM32_TIMERS_DMA_CH1,
> + STM32_TIMERS_DMA_CH2,
> + STM32_TIMERS_DMA_CH3,
> + STM32_TIMERS_DMA_CH4,
> + STM32_TIMERS_DMA_UP,
> + STM32_TIMERS_DMA_TRIG,
> + STM32_TIMERS_DMA_COM,
> + STM32_TIMERS_MAX_DMAS,
> +};
> +
> struct stm32_timers {
> struct clk *clk;
> struct regmap *regmap;
> + phys_addr_t phys_base;
> u32 max_arr;
> + struct dma_chan *dmas[STM32_TIMERS_MAX_DMAS];
> };
> #endif

--
Lee Jones
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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