mmc: sdhci-esdhc-imx: fix incorrect max timeout cout for uSDHC

The default sdhci code use the 1 << 27 as the max timeout counter to
to calculate the max_busy_timeout, however it's not correct for uSDHC
since its the max counter is 1 << 28.
Implement esdhc_get_max_timeout_cout to handle it correctly.
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Dong Aisheng <b29396@freescale.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-esdhc-imx.c

@@ -880,6 +880,14 @@ static void esdhc_reset(struct sdhci_host *host, u8 mask)
 	sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
 }
 
+static unsigned int esdhc_get_max_timeout_count(struct sdhci_host *host)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct pltfm_imx_data *imx_data = pltfm_host->priv;
+
+	return esdhc_is_usdhc(imx_data) ? 1 << 28 : 1 << 27;
+}
+
 static struct sdhci_ops sdhci_esdhc_ops = {
 	.read_l = esdhc_readl_le,
 	.read_w = esdhc_readw_le,
@@ -889,6 +897,7 @@ static struct sdhci_ops sdhci_esdhc_ops = {
 	.set_clock = esdhc_pltfm_set_clock,
 	.get_max_clock = esdhc_pltfm_get_max_clock,
 	.get_min_clock = esdhc_pltfm_get_min_clock,
+	.get_max_timeout_count = esdhc_get_max_timeout_count,
 	.get_ro = esdhc_pltfm_get_ro,
 	.set_bus_width = esdhc_pltfm_set_bus_width,
 	.set_uhs_signaling = esdhc_set_uhs_signaling,