From: Brad Larson <blarson@xxxxxxx>
Add support for mmc hardware reset with a reset-controller
which would need to be enabled in the device tree with
a supporting driver. The default is disabled for all
existing designs.
Signed-off-by: Brad Larson <blarson@xxxxxxx>
---
drivers/mmc/host/sdhci-cadence.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
index c662c63d49fa..35d37b9aba63 100644
--- a/drivers/mmc/host/sdhci-cadence.c
+++ b/drivers/mmc/host/sdhci-cadence.c
@@ -12,6 +12,7 @@
#include <linux/mmc/mmc.h>
#include <linux/of.h>
#include <linux/of_device.h>
+#include <linux/reset.h>
#include "sdhci-pltfm.h"
@@ -70,6 +71,7 @@ struct sdhci_cdns_priv {
spinlock_t wrlock; /* write lock */
bool enhanced_strobe;
void (*priv_writel)(struct sdhci_cdns_priv *priv, u32 val, void __iomem *reg);
+ struct reset_control *rst_hw;
unsigned int nr_phy_params;
struct sdhci_cdns_phy_param phy_params[];
};
@@ -458,6 +460,22 @@ static void sdhci_cdns_hs400_enhanced_strobe(struct mmc_host *mmc,
SDHCI_CDNS_HRS06_MODE_MMC_HS400);
}
+static void sdhci_mmc_hw_reset(struct mmc_host *mmc)
+{
+ struct sdhci_host *host = mmc_priv(mmc);
+ struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
+
+ dev_info(mmc_dev(host->mmc), "emmc hardware reset\n");
+
+ reset_control_assert(priv->rst_hw);
+ /* For eMMC, minimum is 1us but give it 9us for good measure */
+ udelay(9);
+
+ reset_control_deassert(priv->rst_hw);
+ /* For eMMC, minimum is 200us but give it 300us for good measure */
+ usleep_range(300, 1000);
+}
+
static int sdhci_cdns_probe(struct platform_device *pdev)
{
struct sdhci_host *host;
@@ -520,6 +538,17 @@ static int sdhci_cdns_probe(struct platform_device *pdev)
if (ret)
goto free;
+ if (host->mmc->caps & MMC_CAP_HW_RESET) {
+ priv->rst_hw = devm_reset_control_get_optional_exclusive(dev, "hw");
+ if (IS_ERR(priv->rst_hw)) {
+ ret = PTR_ERR(priv->rst_hw);
+ if (ret == -ENOENT)
+ priv->rst_hw = NULL;
+ } else {
+ host->mmc_host_ops.card_hw_reset = sdhci_mmc_hw_reset;
+ }
+ }
+
ret = sdhci_add_host(host);
if (ret)
goto free;
--
2.17.1
