spi: rspi: Round up division to avoid slave overclocking
The calculation of the bit rate divider used a standard C division, which rounds down the quotient. This may lead to a higher bitrate than requested. Round up to avoid this. E.g. on Koelsch, the SPI flash (configured for 30 MHz) was driven at 48.75 MHz. After this patch it's driven at a safe 24.375 MHz. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Mark Brown <broonie@linaro.org>
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@ -266,7 +266,8 @@ static int rspi_set_config_register(struct rspi_data *rspi, int access_size)
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rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
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rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
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/* Sets transfer bit rate */
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/* Sets transfer bit rate */
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spbr = clk_get_rate(rspi->clk) / (2 * rspi->max_speed_hz) - 1;
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spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk),
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2 * rspi->max_speed_hz) - 1;
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rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
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rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
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/* Disable dummy transmission, set 16-bit word access, 1 frame */
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/* Disable dummy transmission, set 16-bit word access, 1 frame */
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@ -302,7 +303,8 @@ static int rspi_rz_set_config_register(struct rspi_data *rspi, int access_size)
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rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
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rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
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/* Sets transfer bit rate */
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/* Sets transfer bit rate */
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spbr = clk_get_rate(rspi->clk) / (2 * rspi->max_speed_hz) - 1;
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spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk),
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2 * rspi->max_speed_hz) - 1;
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rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
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rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
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/* Disable dummy transmission, set byte access */
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/* Disable dummy transmission, set byte access */
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@ -335,7 +337,7 @@ static int qspi_set_config_register(struct rspi_data *rspi, int access_size)
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rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
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rspi_write8(rspi, rspi->sppcr, RSPI_SPPCR);
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/* Sets transfer bit rate */
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/* Sets transfer bit rate */
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spbr = clk_get_rate(rspi->clk) / (2 * rspi->max_speed_hz);
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spbr = DIV_ROUND_UP(clk_get_rate(rspi->clk), 2 * rspi->max_speed_hz);
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rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
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rspi_write8(rspi, clamp(spbr, 0, 255), RSPI_SPBR);
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/* Disable dummy transmission, set byte access */
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/* Disable dummy transmission, set byte access */
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