mmc: tmio: avoid glitches when resetting

[ Upstream commit 2e586f8a5b0ed4a525014a692923ac96f6647816 ]

If we reset because of an error, we need to preserve values for the
clock frequency. Otherwise, glitches may be seen on the bus.

To achieve that, we introduce a 'preserve' parameter to the reset
function and the IP core specific reset callbacks to handle everything
accordingly.

Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20220625131722.1397-1-wsa@kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index 791e180..387f2a4 100644 (file)
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -51,9 +51,6 @@
 #define HOST_MODE_GEN3_32BIT   (HOST_MODE_GEN3_WMODE | HOST_MODE_GEN3_BUSWIDTH)
 #define HOST_MODE_GEN3_64BIT   0
 
-#define CTL_SDIF_MODE  0xe6
-#define SDIF_MODE_HS400                BIT(0)
-
 #define SDHI_VER_GEN2_SDR50    0x490c
 #define SDHI_VER_RZ_A1         0x820b
 /* very old datasheets said 0x490c for SDR104, too. They are wrong! */
@@ -550,23 +547,25 @@ static void renesas_sdhi_scc_reset(struct tmio_mmc_host *host, struct renesas_sd
 }
 
 /* only populated for TMIO_MMC_MIN_RCAR2 */
-static void renesas_sdhi_reset(struct tmio_mmc_host *host)
+static void renesas_sdhi_reset(struct tmio_mmc_host *host, bool preserve)
 {
        struct renesas_sdhi *priv = host_to_priv(host);
        int ret;
        u16 val;
 
-       if (priv->rstc) {
-               reset_control_reset(priv->rstc);
-               /* Unknown why but without polling reset status, it will hang */
-               read_poll_timeout(reset_control_status, ret, ret == 0, 1, 100,
-                                 false, priv->rstc);
-               /* At least SDHI_VER_GEN2_SDR50 needs manual release of reset */
-               sd_ctrl_write16(host, CTL_RESET_SD, 0x0001);
-               priv->needs_adjust_hs400 = false;
-               renesas_sdhi_set_clock(host, host->clk_cache);
-       } else if (priv->scc_ctl) {
-               renesas_sdhi_scc_reset(host, priv);
+       if (!preserve) {
+               if (priv->rstc) {
+                       reset_control_reset(priv->rstc);
+                       /* Unknown why but without polling reset status, it will hang */
+                       read_poll_timeout(reset_control_status, ret, ret == 0, 1, 100,
+                                         false, priv->rstc);
+                       /* At least SDHI_VER_GEN2_SDR50 needs manual release of reset */
+                       sd_ctrl_write16(host, CTL_RESET_SD, 0x0001);
+                       priv->needs_adjust_hs400 = false;
+                       renesas_sdhi_set_clock(host, host->clk_cache);
+               } else if (priv->scc_ctl) {
+                       renesas_sdhi_scc_reset(host, priv);
+               }
        }
 
        if (sd_ctrl_read16(host, CTL_VERSION) >= SDHI_VER_GEN3_SD) {

diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c
index b55a29c..53a2ad9 100644 (file)
--- a/drivers/mmc/host/tmio_mmc.c
+++ b/drivers/mmc/host/tmio_mmc.c
@@ -75,7 +75,7 @@ static void tmio_mmc_set_clock(struct tmio_mmc_host *host,
        tmio_mmc_clk_start(host);
 }
 
-static void tmio_mmc_reset(struct tmio_mmc_host *host)
+static void tmio_mmc_reset(struct tmio_mmc_host *host, bool preserve)
 {
        sd_ctrl_write16(host, CTL_RESET_SDIO, 0x0000);
        usleep_range(10000, 11000);

diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index f936aad..da63193 100644 (file)
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -42,6 +42,7 @@
 #define CTL_DMA_ENABLE 0xd8
 #define CTL_RESET_SD 0xe0
 #define CTL_VERSION 0xe2
+#define CTL_SDIF_MODE 0xe6 /* only known on R-Car 2+ */
 
 /* Definitions for values the CTL_STOP_INTERNAL_ACTION register can take */
 #define TMIO_STOP_STP          BIT(0)
@@ -98,6 +99,9 @@
 /* Definitions for values the CTL_DMA_ENABLE register can take */
 #define DMA_ENABLE_DMASDRW     BIT(1)
 
+/* Definitions for values the CTL_SDIF_MODE register can take */
+#define SDIF_MODE_HS400                BIT(0) /* only known on R-Car 2+ */
+
 /* Define some IRQ masks */
 /* This is the mask used at reset by the chip */
 #define TMIO_MASK_ALL           0x837f031d
@@ -181,7 +185,7 @@ struct tmio_mmc_host {
        int (*multi_io_quirk)(struct mmc_card *card,
                              unsigned int direction, int blk_size);
        int (*write16_hook)(struct tmio_mmc_host *host, int addr);
-       void (*reset)(struct tmio_mmc_host *host);
+       void (*reset)(struct tmio_mmc_host *host, bool preserve);
        bool (*check_retune)(struct tmio_mmc_host *host, struct mmc_request *mrq);
        void (*fixup_request)(struct tmio_mmc_host *host, struct mmc_request *mrq);
        unsigned int (*get_timeout_cycles)(struct tmio_mmc_host *host);

diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
index a5850d8..437048b 100644 (file)
--- a/drivers/mmc/host/tmio_mmc_core.c
+++ b/drivers/mmc/host/tmio_mmc_core.c
@@ -179,8 +179,17 @@ static void tmio_mmc_set_bus_width(struct tmio_mmc_host *host,
        sd_ctrl_write16(host, CTL_SD_MEM_CARD_OPT, reg);
 }
 
-static void tmio_mmc_reset(struct tmio_mmc_host *host)
+static void tmio_mmc_reset(struct tmio_mmc_host *host, bool preserve)
 {
+       u16 card_opt, clk_ctrl, sdif_mode;
+
+       if (preserve) {
+               card_opt = sd_ctrl_read16(host, CTL_SD_MEM_CARD_OPT);
+               clk_ctrl = sd_ctrl_read16(host, CTL_SD_CARD_CLK_CTL);
+               if (host->pdata->flags & TMIO_MMC_MIN_RCAR2)
+                       sdif_mode = sd_ctrl_read16(host, CTL_SDIF_MODE);
+       }
+
        /* FIXME - should we set stop clock reg here */
        sd_ctrl_write16(host, CTL_RESET_SD, 0x0000);
        usleep_range(10000, 11000);
@@ -190,7 +199,7 @@ static void tmio_mmc_reset(struct tmio_mmc_host *host)
        tmio_mmc_abort_dma(host);
 
        if (host->reset)
-               host->reset(host);
+               host->reset(host, preserve);
 
        sd_ctrl_write32_as_16_and_16(host, CTL_IRQ_MASK, host->sdcard_irq_mask_all);
        host->sdcard_irq_mask = host->sdcard_irq_mask_all;
@@ -206,6 +215,13 @@ static void tmio_mmc_reset(struct tmio_mmc_host *host)
                sd_ctrl_write16(host, CTL_TRANSACTION_CTL, 0x0001);
        }
 
+       if (preserve) {
+               sd_ctrl_write16(host, CTL_SD_MEM_CARD_OPT, card_opt);
+               sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, clk_ctrl);
+               if (host->pdata->flags & TMIO_MMC_MIN_RCAR2)
+                       sd_ctrl_write16(host, CTL_SDIF_MODE, sdif_mode);
+       }
+
        if (host->mmc->card)
                mmc_retune_needed(host->mmc);
 }
@@ -248,7 +264,7 @@ static void tmio_mmc_reset_work(struct work_struct *work)
 
        spin_unlock_irqrestore(&host->lock, flags);
 
-       tmio_mmc_reset(host);
+       tmio_mmc_reset(host, true);
 
        /* Ready for new calls */
        host->mrq = NULL;
@@ -961,7 +977,7 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
                tmio_mmc_power_off(host);
                /* For R-Car Gen2+, we need to reset SDHI specific SCC */
                if (host->pdata->flags & TMIO_MMC_MIN_RCAR2)
-                       tmio_mmc_reset(host);
+                       tmio_mmc_reset(host, false);
 
                host->set_clock(host, 0);
                break;
@@ -1189,7 +1205,7 @@ int tmio_mmc_host_probe(struct tmio_mmc_host *_host)
                _host->sdcard_irq_mask_all = TMIO_MASK_ALL;
 
        _host->set_clock(_host, 0);
-       tmio_mmc_reset(_host);
+       tmio_mmc_reset(_host, false);
 
        spin_lock_init(&_host->lock);
        mutex_init(&_host->ios_lock);
@@ -1285,7 +1301,7 @@ int tmio_mmc_host_runtime_resume(struct device *dev)
        struct tmio_mmc_host *host = dev_get_drvdata(dev);
 
        tmio_mmc_clk_enable(host);
-       tmio_mmc_reset(host);
+       tmio_mmc_reset(host, false);
 
        if (host->clk_cache)
                host->set_clock(host, host->clk_cache);