On 04/17/2018 09:12 AM, Lee Jones wrote:
> On Mon, 16 Apr 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 add routine to implement burst reads using DMA from timer registers.
>> This is exported. So, it can be used by child drivers, PWM capture
>> for instance (but not limited to).
>>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
>> Reviewed-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxx>
>> ---
>> Changes in v4:
>> - Lee's comments: Add kerneldoc header, better format comments.
>> Changes in v3:
>> - Basically Lee's comments:
>> - rather create a struct stm32_timers_dma, and place a reference to it
>> in existing ddata (instead of adding priv struct).
>> - rather use a struct device in exported routine prototype, and use
>> standard helpers instead of ddata. Get rid of to_stm32_timers_priv().
>> - simplify error handling in probe (remove a goto)
>> - comment on devm_of_platform_*populate() usage.
>>
>> Changes in v2:
>> - Abstract DMA handling from child driver: move it to MFD core
>> - Add comments on optional dma support
>> ---
>> drivers/mfd/stm32-timers.c | 227 ++++++++++++++++++++++++++++++++++++++-
>> include/linux/mfd/stm32-timers.h | 32 ++++++
>> 2 files changed, 257 insertions(+), 2 deletions(-)
>
> [...]
>
>> diff --git a/include/linux/mfd/stm32-timers.h b/include/linux/mfd/stm32-timers.h
>> index 2aadab6..a04d7a1 100644
>> --- a/include/linux/mfd/stm32-timers.h
>> +++ b/include/linux/mfd/stm32-timers.h
>> @@ -8,6 +8,8 @@
>> #define _LINUX_STM32_GPTIMER_H_
>>
>> #include <linux/clk.h>
>> +#include <linux/dmaengine.h>
>> +#include <linux/dma-mapping.h>
>> #include <linux/regmap.h>
>
> [...]
>
>> +struct stm32_timers_dma;
>> +
>> struct stm32_timers {
>> struct clk *clk;
>> struct regmap *regmap;
>> u32 max_arr;
>> + struct stm32_timers_dma *dma; /* Only to be used by the parent */
>
> I'm confused. I thought the point of putting this comment in was so
> that you could place the definition of 'stm32_timers_dma' and remove
> the forward declaration?
Hi Lee,
Sorry, if I miss-understood the point then. So, do you wish I both:
- move the full struct definition in above header ?
- and keep this comment ?
+/**
+ * struct stm32_timers_dma - STM32 timer DMA handling.
+ * @completion: end of DMA transfer completion
+ * @phys_base: control registers physical base address
+ * @lock: protect DMA access
+ * @chan: DMA channel in use
+ * @chans: DMA channels available for this timer instance
+ */
+struct stm32_timers_dma {
+ struct completion completion;
+ phys_addr_t phys_base;
+ struct mutex lock;
+ struct dma_chan *chan;
+ struct dma_chan *chans[STM32_TIMERS_MAX_DMAS];
+};
This will basically expose the struct to child drivers. But I'm ok if
you think this is acceptable.
I can send a V5 if you wish...
Please advise,
Best regards,
Fabrice
>
>> };
>> +
>> +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);
>> #endif
>
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