diff mbox series

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

Message ID 20230119035136.21603-15-blarson@amd.com
State New
Headers
Series Support AMD Pensando Elba SoC |

Commit Message

Brad Larson Jan. 19, 2023, 3:51 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

Philipp Zabel Jan. 19, 2023, 9:34 a.m. UTC | #1 
Hi Brad,

On Wed, Jan 18, 2023 at 07:51:35PM -0800, Brad Larson wrote:
> 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(+)
> 
> 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 @@
[...]
>  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;

The optional reset_control_get variants return NULL instead of -ENOENT
if no reset is specified.

This should return on any error instead.

> +		} else {
> +			host->mmc_host_ops.card_hw_reset = sdhci_cdns_mmc_hw_reset;

This probably shouldn't be set if reset_control_get_optional returned NULL.

> +		}
> +	}
> +
>  	ret = sdhci_add_host(host);

regards
Philipp
Brad Larson Feb. 7, 2023, 8:53 p.m. UTC | #2 
Hi Philipp,

On Thu, Jan 19, 2023 at 10:34, Philipp Zabel wrote:
> On Wed, Jan 18, 2023 at 07:51:35PM -0800, Brad Larson wrote:
>> 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(+)
>> 
>> 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 @@
[...]
>>  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;
>
> The optional reset_control_get variants return NULL instead of -ENOENT
> if no reset is specified.
>
> This should return on any error instead.
>
>> +		} else {
>> +			host->mmc_host_ops.card_hw_reset = sdhci_cdns_mmc_hw_reset;
>
> This probably shouldn't be set if reset_control_get_optional returned NULL.
[...]

Thanks I see now with the argument optional=true in __of_reset_control_get() it is
returning NULL and not -ENOENT.  This is the updated version.

+       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))
+                       return dev_err_probe(mmc_dev(host->mmc), PTR_ERR(priv->rst_hw),
+                                            "reset controller error\n");
+               if (priv->rst_hw)
+                       host->mmc_host_ops.card_hw_reset = sdhci_cdns_mmc_hw_reset;
+       }

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;