[PATCH V20 11/22] mmc: sdhci-uhs2: add reset function

Victor Shih
2024-09-05T10:20:53Z

Sdhci_uhs2_reset() does a UHS-II specific reset operation.

Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Victor Shih <victor.shih@genesyslogic.com.tw>
---

Updates in V17:
- Move the sdhci_uhs2_reset_cmd_data() to the other patch it was used
for the first time.

Updates in V16:
- Add sdhci_uhs2_reset_cmd_data() function.

Updates in V15:
- Refer the SD Host Controller Standard Specification Section 3.10
to add reset command data mechanism.

Updates in V14:
- Since mmc_card_uhs2() is the same as sdhci_uhs2_mode(), so drop
sdhci_uhs2_mode() and use mmc_card_uhs2() instead of sdhci_uhs2_mode().

Updates in V13:
- Use ios timing to stead MMC_UHS2_SUPPORT for indicate the UHS2 mode.

Updates in V8:
- Adjust the position of matching brackets.

Updates in V6:
- Remove unnecessary functions and simplify code.

---

drivers/mmc/host/sdhci-uhs2.c | 37 +++++++++++++++++++++++++++++++++++
drivers/mmc/host/sdhci-uhs2.h | 1 +
2 files changed, 38 insertions(+)

diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
index 9cb0f1b2a37d..3d16f1ef9344 100644
--- a/drivers/mmc/host/sdhci-uhs2.c
+++ b/drivers/mmc/host/sdhci-uhs2.c
@@ -10,7 +10,9 @@
* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
*/

+#include <linux/delay.h>
#include <linux/module.h>
+#include <linux/iopoll.h>

#include "sdhci.h"
#include "sdhci-uhs2.h"
@@ -21,6 +23,8 @@
#define SDHCI_UHS2_DUMP(f, x...) \
pr_err("%s: " DRIVER_NAME ": " f, mmc_hostname(host->mmc), ## x)

+#define UHS2_RESET_TIMEOUT_100MS 100000
+
void sdhci_uhs2_dump_regs(struct sdhci_host *host)
{
if (!(mmc_card_uhs2(host->mmc)))
@@ -49,6 +53,39 @@ void sdhci_uhs2_dump_regs(struct sdhci_host *host)
}
EXPORT_SYMBOL_GPL(sdhci_uhs2_dump_regs);

+/*****************************************************************************\
+ * *
+ * Low level functions *
+ * *
+\*****************************************************************************/
+
+/**
+ * sdhci_uhs2_reset - invoke SW reset
+ * @host: SDHCI host
+ * @mask: Control mask
+ *
+ * Invoke SW reset, depending on a bit in @mask and wait for completion.
+ */
+void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask)
+{
+ u32 val;
+
+ sdhci_writew(host, mask, SDHCI_UHS2_SW_RESET);
+
+ if (mask & SDHCI_UHS2_SW_RESET_FULL)
+ host->clock = 0;
+
+ /* hw clears the bit when it's done */
+ if (read_poll_timeout_atomic(sdhci_readw, val, !(val & mask), 10,
+ UHS2_RESET_TIMEOUT_100MS, true, host, SDHCI_UHS2_SW_RESET)) {
+ pr_warn("%s: %s: Reset 0x%x never completed. %s: clean reset bit.\n", __func__,
+ mmc_hostname(host->mmc), (int)mask, mmc_hostname(host->mmc));
+ sdhci_writeb(host, 0, SDHCI_UHS2_SW_RESET);
+ return;
+ }
+}
+EXPORT_SYMBOL_GPL(sdhci_uhs2_reset);
+
/*****************************************************************************\
* *
* Driver init/exit *
diff --git a/drivers/mmc/host/sdhci-uhs2.h b/drivers/mmc/host/sdhci-uhs2.h
index 2bfe18d29bca..caaf9fba4975 100644
--- a/drivers/mmc/host/sdhci-uhs2.h
+++ b/drivers/mmc/host/sdhci-uhs2.h
@@ -177,5 +177,6 @@
struct sdhci_host;

void sdhci_uhs2_dump_regs(struct sdhci_host *host);
+void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask);

#endif /* __SDHCI_UHS2_H */
--
2.25.1