This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
that support transfer of dummy cycles by the hardware directly.
For controller with this flag set, spi-mem driver will skip dummy bytes
transfer in the spi message.
Controller drivers can get the number of dummy cycles from spi_message.
Signed-off-by: Sowjanya Komatineni <[email protected]>
---
drivers/spi/spi-mem.c | 18 +++++++++++-------
include/linux/spi/spi.h | 8 ++++++++
2 files changed, 19 insertions(+), 7 deletions(-)
diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index f3a3f19..38a523b 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -350,13 +350,17 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
}
if (op->dummy.nbytes) {
- memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
- xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
- xfers[xferpos].len = op->dummy.nbytes;
- xfers[xferpos].tx_nbits = op->dummy.buswidth;
- spi_message_add_tail(&xfers[xferpos], &msg);
- xferpos++;
- totalxferlen += op->dummy.nbytes;
+ if (ctlr->flags & SPI_MASTER_USES_HW_DUMMY_CYCLES) {
+ msg.dummy_cycles = (op->dummy.nbytes * 8) / op->dummy.buswidth;
+ } else {
+ memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
+ xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
+ xfers[xferpos].len = op->dummy.nbytes;
+ xfers[xferpos].tx_nbits = op->dummy.buswidth;
+ spi_message_add_tail(&xfers[xferpos], &msg);
+ xferpos++;
+ totalxferlen += op->dummy.nbytes;
+ }
}
if (op->data.nbytes) {
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index aa09fdc..2024149 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -512,6 +512,8 @@ struct spi_controller {
#define SPI_MASTER_GPIO_SS BIT(5) /* GPIO CS must select slave */
+#define SPI_MASTER_USES_HW_DUMMY_CYCLES BIT(6) /* HW dummy bytes transfer */
+
/* flag indicating this is an SPI slave controller */
bool slave;
@@ -1022,6 +1024,12 @@ struct spi_message {
unsigned actual_length;
int status;
+ /*
+ * dummy cycles in the message transfer. This is used by the controller
+ * drivers supports transfer of dummy cycles directly by the hardware.
+ */
+ u8 dummy_cycles;
+
/* for optional use by whatever driver currently owns the
* spi_message ... between calls to spi_async and then later
* complete(), that's the spi_controller controller driver.
--
2.7.4
On Fri, Dec 11, 2020 at 09:01:24AM -0800, Sowjanya Komatineni wrote:
> This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
> that support transfer of dummy cycles by the hardware directly.
>
> For controller with this flag set, spi-mem driver will skip dummy bytes
> transfer in the spi message.
>
> Controller drivers can get the number of dummy cycles from spi_message.
Copying more people who've worked on spi-mem for their review - I've not
got such a good perspective on controller features.
> Signed-off-by: Sowjanya Komatineni <[email protected]>
> ---
> drivers/spi/spi-mem.c | 18 +++++++++++-------
> include/linux/spi/spi.h | 8 ++++++++
> 2 files changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index f3a3f19..38a523b 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -350,13 +350,17 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
> }
>
> if (op->dummy.nbytes) {
> - memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
> - xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
> - xfers[xferpos].len = op->dummy.nbytes;
> - xfers[xferpos].tx_nbits = op->dummy.buswidth;
> - spi_message_add_tail(&xfers[xferpos], &msg);
> - xferpos++;
> - totalxferlen += op->dummy.nbytes;
> + if (ctlr->flags & SPI_MASTER_USES_HW_DUMMY_CYCLES) {
> + msg.dummy_cycles = (op->dummy.nbytes * 8) / op->dummy.buswidth;
> + } else {
> + memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
> + xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
> + xfers[xferpos].len = op->dummy.nbytes;
> + xfers[xferpos].tx_nbits = op->dummy.buswidth;
> + spi_message_add_tail(&xfers[xferpos], &msg);
> + xferpos++;
> + totalxferlen += op->dummy.nbytes;
> + }
> }
>
> if (op->data.nbytes) {
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index aa09fdc..2024149 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -512,6 +512,8 @@ struct spi_controller {
>
> #define SPI_MASTER_GPIO_SS BIT(5) /* GPIO CS must select slave */
>
> +#define SPI_MASTER_USES_HW_DUMMY_CYCLES BIT(6) /* HW dummy bytes transfer */
> +
> /* flag indicating this is an SPI slave controller */
> bool slave;
>
> @@ -1022,6 +1024,12 @@ struct spi_message {
> unsigned actual_length;
> int status;
>
> + /*
> + * dummy cycles in the message transfer. This is used by the controller
> + * drivers supports transfer of dummy cycles directly by the hardware.
> + */
> + u8 dummy_cycles;
> +
> /* for optional use by whatever driver currently owns the
> * spi_message ... between calls to spi_async and then later
> * complete(), that's the spi_controller controller driver.
> --
> 2.7.4
>
Sorry mark mixed patches went out.
Will resend v2 and will add other people you have CC'd as well
On 12/11/20 10:33 AM, Mark Brown wrote:
> On Fri, Dec 11, 2020 at 09:01:24AM -0800, Sowjanya Komatineni wrote:
>> This patch adds a flag SPI_MASTER_USES_HW_DUMMY_CYCLES for the controllers
>> that support transfer of dummy cycles by the hardware directly.
>>
>> For controller with this flag set, spi-mem driver will skip dummy bytes
>> transfer in the spi message.
>>
>> Controller drivers can get the number of dummy cycles from spi_message.
> Copying more people who've worked on spi-mem for their review - I've not
> got such a good perspective on controller features.
>
>> Signed-off-by: Sowjanya Komatineni <[email protected]>
>> ---
>> drivers/spi/spi-mem.c | 18 +++++++++++-------
>> include/linux/spi/spi.h | 8 ++++++++
>> 2 files changed, 19 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
>> index f3a3f19..38a523b 100644
>> --- a/drivers/spi/spi-mem.c
>> +++ b/drivers/spi/spi-mem.c
>> @@ -350,13 +350,17 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
>> }
>>
>> if (op->dummy.nbytes) {
>> - memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
>> - xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
>> - xfers[xferpos].len = op->dummy.nbytes;
>> - xfers[xferpos].tx_nbits = op->dummy.buswidth;
>> - spi_message_add_tail(&xfers[xferpos], &msg);
>> - xferpos++;
>> - totalxferlen += op->dummy.nbytes;
>> + if (ctlr->flags & SPI_MASTER_USES_HW_DUMMY_CYCLES) {
>> + msg.dummy_cycles = (op->dummy.nbytes * 8) / op->dummy.buswidth;
>> + } else {
>> + memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
>> + xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
>> + xfers[xferpos].len = op->dummy.nbytes;
>> + xfers[xferpos].tx_nbits = op->dummy.buswidth;
>> + spi_message_add_tail(&xfers[xferpos], &msg);
>> + xferpos++;
>> + totalxferlen += op->dummy.nbytes;
>> + }
>> }
>>
>> if (op->data.nbytes) {
>> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
>> index aa09fdc..2024149 100644
>> --- a/include/linux/spi/spi.h
>> +++ b/include/linux/spi/spi.h
>> @@ -512,6 +512,8 @@ struct spi_controller {
>>
>> #define SPI_MASTER_GPIO_SS BIT(5) /* GPIO CS must select slave */
>>
>> +#define SPI_MASTER_USES_HW_DUMMY_CYCLES BIT(6) /* HW dummy bytes transfer */
>> +
>> /* flag indicating this is an SPI slave controller */
>> bool slave;
>>
>> @@ -1022,6 +1024,12 @@ struct spi_message {
>> unsigned actual_length;
>> int status;
>>
>> + /*
>> + * dummy cycles in the message transfer. This is used by the controller
>> + * drivers supports transfer of dummy cycles directly by the hardware.
>> + */
>> + u8 dummy_cycles;
>> +
>> /* for optional use by whatever driver currently owns the
>> * spi_message ... between calls to spi_async and then later
>> * complete(), that's the spi_controller controller driver.
>> --
>> 2.7.4