mmc: SDHI: add SoC specific workaround via HW version

One of Renesas SDHI chip needs workaround to use it, and, we can judge
it based on chip version.  This patch adds very quick-hack workaround
method, since we still don't know how many chips need workaround in
the future.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sh_mobile_sdhi.c

@@ -33,6 +33,8 @@
 
 #include "tmio_mmc.h"
 
+#define EXT_ACC           0xe4
+
 struct sh_mobile_sdhi_of_data {
 	unsigned long tmio_flags;
 };
@@ -137,6 +139,7 @@ static int sh_mobile_sdhi_probe(struct platform_device *pdev)
 	int irq, ret, i = 0;
 	bool multiplexed_isr = true;
 	struct tmio_mmc_dma *dma_priv;
+	u16 ver;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res)
@@ -218,6 +221,14 @@ static int sh_mobile_sdhi_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto eprobe;
 
+	/*
+	 * FIXME:
+	 * this Workaround can be more clever method
+	 */
+	ver = sd_ctrl_read16(host, CTL_VERSION);
+	if (ver == 0xCB0D)
+		sd_ctrl_write16(host, EXT_ACC, 1);
+
 	/*
 	 * Allow one or more specific (named) ISRs or
 	 * one or more multiplexed (un-named) ISRs.

include/linux/mmc/tmio.h

@@ -33,6 +33,7 @@
 #define CTL_SDIO_IRQ_MASK 0x38
 #define CTL_DMA_ENABLE 0xd8
 #define CTL_RESET_SD 0xe0
+#define CTL_VERSION 0xe2
 #define CTL_SDIO_REGS 0x100
 #define CTL_CLK_AND_WAIT_CTL 0x138
 #define CTL_RESET_SDIO 0x1e0