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spi: rspi: Use requested instead of maximum bit rate 

Currently, the RSPI driver always tries to use the maximum configured
bit rate for communicating with a slave device, even if the transfer(s)
in the current message specify a lower rate.

Use the mininum rate specified in the message instead.
Rename rspi_data.max_speed_hz accordingly.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200608095940.30516-3-geert+renesas@glider.be
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Geert Uytterhoeven 2020-06-08 11:59:34 +02:00 committed by Mark Brown
parent 9ec8ade812
commit e0fe70051f
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 21 additions and 7 deletions
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28
drivers/spi/spi-rspi.c
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@ -179,7 +179,7 @@
struct rspi_data { struct rspi_data {
void __iomem *addr; void __iomem *addr;
u32 max_speed_hz; u32 speed_hz;
struct spi_controller *ctlr; struct spi_controller *ctlr;
struct platform_device *pdev; struct platform_device *pdev;
wait_queue_head_t wait; wait_queue_head_t wait;
@ -258,8 +258,7 @@ static int rspi_set_config_register(struct rspi_data *rspi, int access_size)
rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR); rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
/* Sets transfer bit rate */ /* Sets transfer bit rate */
spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->speed_hz) - 1;
2 * rspi->max_speed_hz) - 1;
rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR); rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
/* Disable dummy transmission, set 16-bit word access, 1 frame */ /* Disable dummy transmission, set 16-bit word access, 1 frame */
@ -299,14 +298,14 @@ static int rspi_rz_set_config_register(struct rspi_data *rspi, int access_size)
clksrc = clk_get_rate(rspi->clk); clksrc = clk_get_rate(rspi->clk);
while (div < 3) { while (div < 3) {
if (rspi->max_speed_hz >= clksrc/4) /* 4=(CLK/2)/2 */ if (rspi->speed_hz >= clksrc/4) /* 4=(CLK/2)/2 */
break; break;
div++; div++;
clksrc /= 2; clksrc /= 2;
} }
/* Sets transfer bit rate */ /* Sets transfer bit rate */
spbr = DIV_ROUND_UP(clksrc, 2 * rspi->max_speed_hz) - 1; spbr = DIV_ROUND_UP(clksrc, 2 * rspi->speed_hz) - 1;
rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR); rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
rspi->spcmd |= div << 2; rspi->spcmd |= div << 2;
@ -341,7 +340,7 @@ static int qspi_set_config_register(struct rspi_data *rspi, int access_size)
rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR); rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
/* Sets transfer bit rate */ /* Sets transfer bit rate */
spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->max_speed_hz); spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->speed_hz);
rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR); rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
/* Disable dummy transmission, set byte access */ /* Disable dummy transmission, set byte access */
@ -949,9 +948,24 @@ static int rspi_prepare_message(struct spi_controller *ctlr,
{ {
struct rspi_data *rspi = spi_controller_get_devdata(ctlr); struct rspi_data *rspi = spi_controller_get_devdata(ctlr);
struct spi_device *spi = msg->spi; struct spi_device *spi = msg->spi;
const struct spi_transfer *xfer;
int ret; int ret;
rspi->max_speed_hz = spi->max_speed_hz; /*
* As the Bit Rate Register must not be changed while the device is
* active, all transfers in a message must use the same bit rate.
* In theory, the sequencer could be enabled, and each Command Register
* could divide the base bit rate by a different value.
* However, most RSPI variants do not have Transfer Data Length
* Multiplier Setting Registers, so each sequence step would be limited
* to a single word, making this feature unsuitable for large
* transfers, which would gain most from it.
*/
rspi->speed_hz = spi->max_speed_hz;
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
if (xfer->speed_hz < rspi->speed_hz)
rspi->speed_hz = xfer->speed_hz;
}
rspi->spcmd = SPCMD_SSLKP; rspi->spcmd = SPCMD_SSLKP;
if (spi->mode & SPI_CPOL) if (spi->mode & SPI_CPOL)