MMC: AU1xMMC: Allow platforms to disable host capabilities

Although the hardware supports a 4/8bit SD interface and the driver
unconditionally advertises all hardware caps to the MMC core, not all
datalines may actually be wired up.  This patch introduces another
field to au1xmmc platform data allowing platforms to disable certain
advanced host controller features.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
To: linux-mmc@vger.kernel.org
CC: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: http://patchwork.linux-mips.org/patch/460/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mach-au1x00/au1100_mmc.h

@@ -46,6 +46,7 @@ struct au1xmmc_platform_data {
 	int(*card_readonly)(void *mmc_host);
 	void(*set_power)(void *mmc_host, int state);
 	struct led_classdev *led;
+	unsigned long mask_host_caps;
 };
 
 #define SD0_BASE	0xB0600000

drivers/mmc/host/au1xmmc.c

@@ -1017,6 +1017,10 @@ static int __devinit au1xmmc_probe(struct platform_device *pdev)
 	} else
 		mmc->caps |= MMC_CAP_NEEDS_POLL;
 
+	/* platform may not be able to use all advertised caps */
+	if (host->platdata)
+		mmc->caps &= ~(host->platdata->mask_host_caps);
+
 	tasklet_init(&host->data_task, au1xmmc_tasklet_data,
 			(unsigned long)host);