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Commit 4406433d authored by Ludovic Desroches's avatar Ludovic Desroches Committed by Ulf Hansson
Browse files

mmc: sdhci-of-at91: add presets setup 



The controller claims to support SDR104. In fact, it only supports a
degraded SDR104 since the maximum frequency of the SD clock is 120 MHz
instead of 208 MHz.
The sdhci core is unaware of it and will compute a wrong clock divider.
We can deal with this specific case by using presets.

Signed-off-by: default avatarLudovic Desroches <ludovic.desroches@atmel.com>
Acked-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
parent 488aab3d

drivers/mmc/host/sdhci-of-at91.c

+26 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/delay.h>

#include <linux/err.h>

#include <linux/io.h>

#include <linux/kernel.h>

#include <linux/mmc/host.h>

#include <linux/mmc/slot-gpio.h>

#include <linux/module.h>
@@ -32,6 +33,8 @@ 
#define		SDMMC_CACR_CAPWREN	BIT(0)

#define		SDMMC_CACR_KEY		(0x46 << 8)



#define SDHCI_AT91_PRESET_COMMON_CONF	0x400 /* drv type B, programmable clock mode */



struct sdhci_at91_priv {

	struct clk *hclock;

	struct clk *gck;
@@ -163,6 +166,7 @@ static int sdhci_at91_probe(struct platform_device *pdev) 
	unsigned int			clk_base, clk_mul;

	unsigned int			gck_rate, real_gck_rate;

	int				ret;

	unsigned int			preset_div;



	match = of_match_device(sdhci_at91_dt_match, &pdev->dev);

	if (!match)
@@ -230,6 +234,28 @@ static int sdhci_at91_probe(struct platform_device *pdev) 
			 clk_mul, real_gck_rate);

	}



	/*

	 * We have to set preset values because it depends on the clk_mul

	 * value. Moreover, SDR104 is supported in a degraded mode since the

	 * maximum sd clock value is 120 MHz instead of 208 MHz. For that

	 * reason, we need to use presets to support SDR104.

	 */

	preset_div = DIV_ROUND_UP(real_gck_rate, 24000000) - 1;

	writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,

	       host->ioaddr + SDHCI_PRESET_FOR_SDR12);

	preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1;

	writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,

	       host->ioaddr + SDHCI_PRESET_FOR_SDR25);

	preset_div = DIV_ROUND_UP(real_gck_rate, 100000000) - 1;

	writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,

	       host->ioaddr + SDHCI_PRESET_FOR_SDR50);

	preset_div = DIV_ROUND_UP(real_gck_rate, 120000000) - 1;

	writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,

	       host->ioaddr + SDHCI_PRESET_FOR_SDR104);

	preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1;

	writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,

	       host->ioaddr + SDHCI_PRESET_FOR_DDR50);



	clk_prepare_enable(priv->mainck);

	clk_prepare_enable(priv->gck);