From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Mark Brown <broonie@kernel.org>
Cc: Chris Brandt <chris.brandt@renesas.com>,
linux-spi@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
linux-sh@vger.kernel.org,
Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH 6/8] spi: rspi: Increase bit rate range for QSPI
Date: Mon, 08 Jun 2020 09:59:38 +0000 [thread overview]
Message-ID: <20200608095940.30516-7-geert+renesas@glider.be> (raw)
In-Reply-To: <20200608095940.30516-1-geert+renesas@glider.be>
Increase bit rate range for QSPI by extending the range of supported
dividers:
1. QSPI supports a divider of 1, by setting SPBR to zero, increasing
the upper limit from 48.75 to 97.5 MHz,
2. Make use of the Bit Rate Frequency Division Setting field in
Command Registers, to decrease the lower limit from 191 to 24 kbps.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
drivers/spi/spi-rspi.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index ea3f2680d3c13e02..38c0cd7febabf114 100644
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -334,14 +334,26 @@ static int rspi_rz_set_config_register(struct rspi_data *rspi, int access_size)
*/
static int qspi_set_config_register(struct rspi_data *rspi, int access_size)
{
- int spbr;
+ unsigned long clksrc;
+ int brdv = 0, spbr;
/* Sets output mode, MOSI signal, and (optionally) loopback */
rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
/* Sets transfer bit rate */
- spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->speed_hz);
- rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
+ clksrc = clk_get_rate(rspi->clk);
+ if (rspi->speed_hz >= clksrc) {
+ spbr = 0;
+ } else {
+ spbr = DIV_ROUND_UP(clksrc, 2 * rspi->speed_hz);
+ while (spbr > 255 && brdv < 3) {
+ brdv++;
+ spbr = DIV_ROUND_UP(spbr, 2);
+ }
+ spbr = clamp(spbr, 0, 255);
+ }
+ rspi_write8(rspi, spbr, RSPI_SPBR);
+ rspi->spcmd |= SPCMD_BRDV(brdv);
/* Disable dummy transmission, set byte access */
rspi_write8(rspi, 0, RSPI_SPDCR);
--
2.17.1
WARNING: multiple messages have this Message-ID (diff)
From: Geert Uytterhoeven <geert+renesas@glider.be>
To: Mark Brown <broonie@kernel.org>
Cc: Chris Brandt <chris.brandt@renesas.com>,
linux-spi@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
linux-sh@vger.kernel.org,
Geert Uytterhoeven <geert+renesas@glider.be>
Subject: [PATCH 6/8] spi: rspi: Increase bit rate range for QSPI
Date: Mon, 8 Jun 2020 11:59:38 +0200 [thread overview]
Message-ID: <20200608095940.30516-7-geert+renesas@glider.be> (raw)
In-Reply-To: <20200608095940.30516-1-geert+renesas@glider.be>
Increase bit rate range for QSPI by extending the range of supported
dividers:
1. QSPI supports a divider of 1, by setting SPBR to zero, increasing
the upper limit from 48.75 to 97.5 MHz,
2. Make use of the Bit Rate Frequency Division Setting field in
Command Registers, to decrease the lower limit from 191 to 24 kbps.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
drivers/spi/spi-rspi.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index ea3f2680d3c13e02..38c0cd7febabf114 100644
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -334,14 +334,26 @@ static int rspi_rz_set_config_register(struct rspi_data *rspi, int access_size)
*/
static int qspi_set_config_register(struct rspi_data *rspi, int access_size)
{
- int spbr;
+ unsigned long clksrc;
+ int brdv = 0, spbr;
/* Sets output mode, MOSI signal, and (optionally) loopback */
rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
/* Sets transfer bit rate */
- spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->speed_hz);
- rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
+ clksrc = clk_get_rate(rspi->clk);
+ if (rspi->speed_hz >= clksrc) {
+ spbr = 0;
+ } else {
+ spbr = DIV_ROUND_UP(clksrc, 2 * rspi->speed_hz);
+ while (spbr > 255 && brdv < 3) {
+ brdv++;
+ spbr = DIV_ROUND_UP(spbr, 2);
+ }
+ spbr = clamp(spbr, 0, 255);
+ }
+ rspi_write8(rspi, spbr, RSPI_SPBR);
+ rspi->spcmd |= SPCMD_BRDV(brdv);
/* Disable dummy transmission, set byte access */
rspi_write8(rspi, 0, RSPI_SPDCR);
--
2.17.1
next prev parent reply other threads:[~2020-06-08 9:59 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-08 9:59 [PATCH 0/8] spi: rspi: Bit rate improvements Geert Uytterhoeven
2020-06-08 9:59 ` Geert Uytterhoeven
2020-06-08 9:59 ` [PATCH 1/8] spi: rspi: Remove useless .set_config_register() check Geert Uytterhoeven
2020-06-08 9:59 ` Geert Uytterhoeven
2020-06-08 9:59 ` [PATCH 2/8] spi: rspi: Use requested instead of maximum bit rate Geert Uytterhoeven
2020-06-08 9:59 ` Geert Uytterhoeven
2020-06-08 9:59 ` [PATCH 3/8] spi: rspi: Clean up Bit Rate Division Setting handling Geert Uytterhoeven
2020-06-08 9:59 ` Geert Uytterhoeven
2020-06-08 9:59 ` [PATCH 4/8] spi: rspi: Increase bit rate accuracy on RZ/A Geert Uytterhoeven
2020-06-08 9:59 ` Geert Uytterhoeven
2020-06-08 9:59 ` [PATCH 5/8] spi: rspi: Increase bit rate range for RSPI on SH Geert Uytterhoeven
2020-06-08 9:59 ` Geert Uytterhoeven
2020-06-08 9:59 ` Geert Uytterhoeven [this message]
2020-06-08 9:59 ` [PATCH 6/8] spi: rspi: Increase bit rate range for QSPI Geert Uytterhoeven
2020-06-08 9:59 ` [PATCH 7/8] spi: rspi: Fill in spi_transfer.effective_speed_hz Geert Uytterhoeven
2020-06-08 9:59 ` Geert Uytterhoeven
2020-06-08 9:59 ` [PATCH 8/8] spi: rspi: Fill in controller speed limits Geert Uytterhoeven
2020-06-08 9:59 ` Geert Uytterhoeven
2020-06-09 12:54 ` [PATCH 0/8] spi: rspi: Bit rate improvements Mark Brown
2020-06-09 12:54 ` Mark Brown
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