ARM: hisilicon: hikey: Fix eMMC with latest ATF & U-Boot

ATF can leave the MMC IP in a state where U-Boot mmc driver
can't enumerate the eMMC.

This patch provides a mmc0_reset_clk() function like we
already so do sd card controller which resets the IP
when entering U-Boot.

With this patch applied eMMC partitions are successfully
enumerated again.

=> mmc dev 0
switch to partitions #0, OK
mmc0(part 0) is current device
=> mmc part

Partition Map for MMC device 0  --   Partition Type: EFI

Part	Start LBA	End LBA		Name
	Attributes
	Type GUID
	Partition GUID
  1	0x00000800	0x00000fff	"vrl"
	attrs:	0x0000000000000000
	type:	ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
	guid:	496847ab-56a1-4cd5-a1ad-47f4acf055c9
  2	0x00001000	0x000017ff	"vrl_backup"
	attrs:	0x0000000000000000
	type:	ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
	guid:	61a36fc1-8efb-4899-84d8-b61642efa723
  3	0x00001800	0x00001fff	"mcuimage"
<snip>

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>

board/hisilicon/hikey/hikey.c

@@ -295,13 +295,47 @@ static void mmc1_reset_clk(void)
 		data = readl(&peri_sc->rst0_stat);
 	} while (!(data & PERI_RST0_MMC1));
 
-	/* unreset mmc0 clock domain */
+	/* unreset mmc1 clock domain */
 	writel(PERI_RST0_MMC1, &peri_sc->rst0_dis);
 	do {
 		data = readl(&peri_sc->rst0_stat);
 	} while (data & PERI_RST0_MMC1);
 }
 
+static void mmc0_reset_clk(void)
+{
+	unsigned int data;
+
+	/* disable mmc0 bus clock */
+	hi6220_clk_disable(PERI_CLK0_MMC0, &peri_sc->clk0_dis);
+
+	/* enable mmc0 bus clock */
+	hi6220_clk_enable(PERI_CLK0_MMC0, &peri_sc->clk0_en);
+
+	/* reset mmc0 clock domain */
+	writel(PERI_RST0_MMC0, &peri_sc->rst0_en);
+
+	/* bypass mmc0 clock phase */
+	data = readl(&peri_sc->ctrl2);
+	data |= 3;
+	writel(data, &peri_sc->ctrl2);
+
+	/* disable low power */
+	data = readl(&peri_sc->ctrl13);
+	data |= 1 << 3;
+	writel(data, &peri_sc->ctrl13);
+	do {
+		data = readl(&peri_sc->rst0_stat);
+	} while (!(data & PERI_RST0_MMC0));
+
+	/* unreset mmc0 clock domain */
+	writel(PERI_RST0_MMC0, &peri_sc->rst0_dis);
+	do {
+		data = readl(&peri_sc->rst0_stat);
+	} while (data & PERI_RST0_MMC0);
+}
+
+
 /* PMU SSI is the IP that maps the external PMU hi6553 registers as IO */
 static void hi6220_pmussi_init(void)
 {
@@ -349,7 +383,8 @@ static int init_dwmmc(void)
 
 #ifdef CONFIG_MMC_DW
 
-	/* mmc0 clocks are already configured by ATF */
+	/* mmc0 pll is already configured by ATF */
+	mmc0_reset_clk();
 	ret = hi6220_pinmux_config(PERIPH_ID_SDMMC0);
 	if (ret)
 		printf("%s: Error configuring pinmux for eMMC (%d)\n"