diff mbox series

[v9,14/15] mmc: sdhci-cadence: Support mmc hardware reset

Message ID 20230119033918.44117-15-blarson@amd.com (mailing list archive)
State New, archived
Headers show
Series Support AMD Pensando Elba SoC | expand

Commit Message

Brad Larson Jan. 19, 2023, 3:39 a.m. UTC 
Add support for mmc hardware reset using a reset-controller
that 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@amd.com>
---

Changes since v6:
- Previously patch 17/17
- Changed delay after reset_control_assert() from 9 to 3 usec
- Renamed sdhci_mmc_hw_reset() to sdhci_cdns_mmc_hw_reset()

---
 drivers/mmc/host/sdhci-cadence.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

Comments

Arnd Bergmann Jan. 19, 2023, 8:57 a.m. UTC | #1 
On Thu, Jan 19, 2023, at 04:39, Brad Larson wrote:
> 
> +extern unsigned int sdhci_timeout_val;
> +

This declaration should not be in the .c file, and I don't think
there should be a global variable with this overly generic name either.

     Arnd
Brad Larson Feb. 7, 2023, 1:51 a.m. UTC | #2 
On Thu, Jan 19, 2023, at 09:57, Arnd Bergmann wrote:
> On Thu, Jan 19, 2023, at 04:39, Brad Larson wrote:
>> 
>> +extern unsigned int sdhci_timeout_val;
>> +
>
> This declaration should not be in the .c file, and I don't think
> there should be a global variable with this overly generic name either.

Thanks for pointing this out, I've deleted that line.  It was leftover test
code to force a timeout to trigger the reset driver and reset the timeout.

Regards,
Brad
diff mbox series

Patch

diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
index e92aa79a8be2..62321cef41db 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 +460,24 @@  static void sdhci_cdns_hs400_enhanced_strobe(struct mmc_host *mmc,
 					 SDHCI_CDNS_HRS06_MODE_MMC_HS400);
 }
 
+extern unsigned int sdhci_timeout_val;
+
+static void sdhci_cdns_mmc_hw_reset(struct mmc_host *mmc)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
+
+	dev_dbg(mmc_dev(host->mmc), "emmc hardware reset\n");
+
+	reset_control_assert(priv->rst_hw);
+	/* For eMMC, minimum is 1us but give it 3us for good measure */
+	udelay(3);
+
+	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;
@@ -521,6 +541,17 @@  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_cdns_mmc_hw_reset;
+		}
+	}
+
 	ret = sdhci_add_host(host);
 	if (ret)
 		goto free;