[PATCH 1/5] mmc: add eMMC hardware reset support

Adrian Hunter
2011-08-29T13:42:25Z

eMMC's may have a hardware reset line. This patch provides a
host controller operation to implement hardware reset and
a function to reset and reinitialize the card. Also, for MMC,
the reset is always performed before initialization.

The host must set the new host capability MMC_CAP_HW_RESET
to enable hardware reset.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
drivers/mmc/core/core.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++
drivers/mmc/core/mmc.c | 4 +-
include/linux/mmc/card.h | 1 +
include/linux/mmc/core.h | 3 +
include/linux/mmc/host.h | 2 +
include/linux/mmc/mmc.h | 4 ++
6 files changed, 108 insertions(+), 1 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 557856b..3bdb981 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1768,6 +1768,95 @@ int mmc_set_blocklen(struct mmc_card *card, unsigned int blocklen)
}
EXPORT_SYMBOL(mmc_set_blocklen);

+static void mmc_hw_reset_for_init(struct mmc_host *host)
+{
+ if (!(host->caps & MMC_CAP_HW_RESET) || !host->ops->hw_reset)
+ return;
+ mmc_host_clk_hold(host);
+ host->ops->hw_reset(host);
+ mmc_host_clk_release(host);
+}
+
+int mmc_can_reset(struct mmc_card *card)
+{
+ u8 rst_n_function;
+
+ if (!mmc_card_mmc(card))
+ return 0;
+ rst_n_function = card->ext_csd.rst_n_function;
+ if ((rst_n_function & EXT_CSD_RST_N_EN_MASK) != EXT_CSD_RST_N_ENABLED)
+ return 0;
+ return 1;
+}
+EXPORT_SYMBOL(mmc_can_reset);
+
+static int mmc_do_hw_reset(struct mmc_host *host, int check)
+{
+ struct mmc_card *card = host->card;
+
+ if (!host->bus_ops->power_restore)
+ return -EOPNOTSUPP;
+
+ if (!(host->caps & MMC_CAP_HW_RESET) || !host->ops->hw_reset)
+ return -EOPNOTSUPP;
+
+ if (!card)
+ return -EINVAL;
+
+ if (!mmc_can_reset(card))
+ return -EOPNOTSUPP;
+
+ mmc_host_clk_hold(host);
+ mmc_set_clock(host, host->f_init);
+
+ host->ops->hw_reset(host);
+
+ /* If the reset has happened, then a status command will fail */
+ if (check) {
+ struct mmc_command cmd = {0};
+ int err;
+
+ cmd.opcode = MMC_SEND_STATUS;
+ if (!mmc_host_is_spi(card->host))
+ cmd.arg = card->rca << 16;
+ cmd.flags = MMC_RSP_SPI_R2 | MMC_RSP_R1 | MMC_CMD_AC;
+ err = mmc_wait_for_cmd(card->host, &cmd, 0);
+ if (!err) {
+ mmc_host_clk_release(host);
+ return -ENOSYS;
+ }
+ }
+
+ host->card->state &= ~(MMC_STATE_HIGHSPEED | MMC_STATE_HIGHSPEED_DDR);
+ if (mmc_host_is_spi(host)) {
+ host->ios.chip_select = MMC_CS_HIGH;
+ host->ios.bus_mode = MMC_BUSMODE_PUSHPULL;
+ } else {
+ host->ios.chip_select = MMC_CS_DONTCARE;
+ host->ios.bus_mode = MMC_BUSMODE_OPENDRAIN;
+ }
+ host->ios.bus_width = MMC_BUS_WIDTH_1;
+ host->ios.timing = MMC_TIMING_LEGACY;
+ host->ios.ddr = MMC_SDR_MODE;
+ mmc_set_ios(host);
+
+ mmc_host_clk_release(host);
+
+ return host->bus_ops->power_restore(host);
+}
+
+int mmc_hw_reset(struct mmc_host *host)
+{
+ return mmc_do_hw_reset(host, 0);
+}
+EXPORT_SYMBOL(mmc_hw_reset);
+
+int mmc_hw_reset_check(struct mmc_host *host)
+{
+ return mmc_do_hw_reset(host, 1);
+}
+EXPORT_SYMBOL(mmc_hw_reset_check);
+
static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
{
host->f_init = freq;
@@ -1779,6 +1868,12 @@ static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
mmc_power_up(host);

/*
+ * Some eMMCs (with VCCQ always on) may not be reset after power up, so
+ * do a hardware reset if possible.
+ */
+ mmc_hw_reset_for_init(host);
+
+ /*
* sdio_reset sends CMD52 to reset card. Since we do not know
* if the card is being re-initialized, just send it. CMD52
* should be ignored by SD/eMMC cards.
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 5700b1c..e090a87 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -402,8 +402,10 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
ext_csd[EXT_CSD_TRIM_MULT];
}

- if (card->ext_csd.rev >= 5)
+ if (card->ext_csd.rev >= 5) {
card->ext_csd.rel_param = ext_csd[EXT_CSD_WR_REL_PARAM];
+ card->ext_csd.rst_n_function = ext_csd[EXT_CSD_RST_N_FUNCTION];
+ }

if (ext_csd[EXT_CSD_ERASED_MEM_CONT])
card->erased_byte = 0xFF;
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index b460fc2..a45c5b8 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -50,6 +50,7 @@ struct mmc_ext_csd {
u8 rel_sectors;
u8 rel_param;
u8 part_config;
+ u8 rst_n_function;
unsigned int part_time; /* Units: ms */
unsigned int sa_timeout; /* Units: 100ns */
unsigned int hs_max_dtr;
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index b8b1b7a..56e5625 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -162,6 +162,9 @@ extern int mmc_erase_group_aligned(struct mmc_card *card, unsigned int from,
extern unsigned int mmc_calc_max_discard(struct mmc_card *card);

extern int mmc_set_blocklen(struct mmc_card *card, unsigned int blocklen);
+extern int mmc_hw_reset(struct mmc_host *host);
+extern int mmc_hw_reset_check(struct mmc_host *host);
+extern int mmc_can_reset(struct mmc_card *card);

extern void mmc_set_data_timeout(struct mmc_data *, const struct mmc_card *);
extern unsigned int mmc_align_data_size(struct mmc_card *, unsigned int);
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 4c4bddf..85b5626 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -148,6 +148,7 @@ struct mmc_host_ops {
int (*execute_tuning)(struct mmc_host *host);
void (*enable_preset_value)(struct mmc_host *host, bool enable);
int (*select_drive_strength)(unsigned int max_dtr, int host_drv, int card_drv);
+ void (*hw_reset)(struct mmc_host *host);
};

struct mmc_card;
@@ -230,6 +231,7 @@ struct mmc_host {
#define MMC_CAP_MAX_CURRENT_600 (1 << 28) /* Host max current limit is 600mA */
#define MMC_CAP_MAX_CURRENT_800 (1 << 29) /* Host max current limit is 800mA */
#define MMC_CAP_CMD23 (1 << 30) /* CMD23 supported. */
+#define MMC_CAP_HW_RESET (1 << 31) /* Hardware reset */

mmc_pm_flag_t pm_caps; /* supported pm features */

diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
index 5a794cb..ed8fca8 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -272,6 +272,7 @@ struct _mmc_csd {

#define EXT_CSD_PARTITION_ATTRIBUTE 156 /* R/W */
#define EXT_CSD_PARTITION_SUPPORT 160 /* RO */
+#define EXT_CSD_RST_N_FUNCTION 162 /* R/W */
#define EXT_CSD_WR_REL_PARAM 166 /* RO */
#define EXT_CSD_ERASE_GROUP_DEF 175 /* R/W */
#define EXT_CSD_PART_CONFIG 179 /* R/W */
@@ -328,6 +329,9 @@ struct _mmc_csd {
#define EXT_CSD_SEC_BD_BLK_EN BIT(2)
#define EXT_CSD_SEC_GB_CL_EN BIT(4)

+#define EXT_CSD_RST_N_EN_MASK 0x3
+#define EXT_CSD_RST_N_ENABLED 1 /* RST_n is enabled on card */
+
/*
* MMC_SWITCH access modes
*/
--
1.7.6