[PATCH v9 08/10] mmc: sdhci: add function to get retunig timer count

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According to SD host spec (Capabilities Register, offset 0x40<43:40>),
if timer count for retuning return 0xF, it means get information from other source.

Signed-off-by: Kevin Liu <kliu5@xxxxxxxxxxx>
---
 drivers/mmc/host/sdhci.c |    8 ++++++++
 drivers/mmc/host/sdhci.h |    1 +
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 3db5f10..20a3c53 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2970,6 +2970,14 @@ int sdhci_add_host(struct sdhci_host *host)
 	/* Initial value for re-tuning timer count */
 	host->tuning_count = (caps[1] & SDHCI_RETUNING_TIMER_COUNT_MASK) >>
 			      SDHCI_RETUNING_TIMER_COUNT_SHIFT;
+	if (host->tuning_count == 0xF) {
+		if (host->ops->get_tuning_count)
+			host->tuning_count =
+				host->ops->get_tuning_count(host) & 0xF;
+		else
+			pr_err("%s: Hardware doesn't specify tuning count.\n",
+				mmc_hostname(mmc));
+	}
 
 	/*
 	 * In case Re-tuning Timer is not disabled, the actual value of
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 7fe0462..8596f11 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -291,6 +291,7 @@ struct sdhci_ops {
 	void	(*platform_resume)(struct sdhci_host *host);
 	void	(*platform_init)(struct sdhci_host *host);
 	void    (*signal_voltage_switch)(struct sdhci_host *host, u8 vol);
+	unsigned int    (*get_tuning_count)(struct sdhci_host *host);
 };
 
 #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
-- 
1.7.0.4

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