From: Che-Liang Chiou clchiou@chromium.org

Most of time that MMC driver spends on initializing a device is polling OCR (operation conditions register). To decouple this polling loop, device init is split into two parts: The first part fires the OCR query command, and the second part polls the result. So the caller is now no longer bound to the OCR-polling delay; he may fire the query, go somewhere and then come back later for the result.

To use this, call mmc_set_preinit() on any device which needs this.

This can save significant amounts of time on boot (e.g. 200ms) by hiding the MMC init time behind other init.

Signed-off-by: Che-Liang Chiou clchiou@chromium.org Signed-off-by: Simon Glass sjg@chromium.org --- drivers/mmc/mmc.c | 135 ++++++++++++++++++++++++++++++++++++++++------------ include/mmc.h | 30 ++++++++++++ 2 files changed, 134 insertions(+), 31 deletions(-)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index 18a037d..d397326 100644 --- a/drivers/mmc/mmc.c +++ b/drivers/mmc/mmc.c @@ -594,48 +594,70 @@ sd_send_op_cond(struct mmc *mmc) return 0; }

+/* We pass in the cmd since otherwise the init seems to fail */ +static int mmc_send_op_cond_iter(struct mmc *mmc, struct mmc_cmd *cmd, + int use_arg) +{ + int err; + + cmd->cmdidx = MMC_CMD_SEND_OP_COND; + cmd->resp_type = MMC_RSP_R3; + cmd->cmdarg = 0; + if (use_arg && !mmc_host_is_spi(mmc)) { + cmd->cmdarg = + (mmc->voltages & + (mmc->op_cond_response & OCR_VOLTAGE_MASK)) | + (mmc->op_cond_response & OCR_ACCESS_MODE); + + if (mmc->host_caps & MMC_MODE_HC) + cmd->cmdarg |= OCR_HCS; + } + err = mmc_send_cmd(mmc, cmd, NULL); + if (err) + return err; + mmc->op_cond_response = cmd->response[0]; + return 0; +} + int mmc_send_op_cond(struct mmc *mmc) { - int timeout = 10000; struct mmc_cmd cmd; - int err; + int err, i;

/* Some cards seem to need this */ mmc_go_idle(mmc);

/* Asking to the card its capabilities */ - cmd.cmdidx = MMC_CMD_SEND_OP_COND; - cmd.resp_type = MMC_RSP_R3; - cmd.cmdarg = 0; - - err = mmc_send_cmd(mmc, &cmd, NULL); + mmc->op_cond_pending = 1; + for (i = 0; i < 2; i++) { + err = mmc_send_op_cond_iter(mmc, &cmd, i != 0); + if (err) + return err;

- if (err) - return err; + /* exit if not busy (flag seems to be inverted) */ + if (mmc->op_cond_response & OCR_BUSY) + return 0; + } + return IN_PROGRESS; +}

- udelay(1000); +int mmc_complete_op_cond(struct mmc *mmc) +{ + struct mmc_cmd cmd; + int timeout = 1000; + uint start; + int err;

+ mmc->op_cond_pending = 0; + start = get_timer(0); do { - cmd.cmdidx = MMC_CMD_SEND_OP_COND; - cmd.resp_type = MMC_RSP_R3; - cmd.cmdarg = (mmc_host_is_spi(mmc) ? 0 : - (mmc->voltages & - (cmd.response[0] & OCR_VOLTAGE_MASK)) | - (cmd.response[0] & OCR_ACCESS_MODE)); - - if (mmc->host_caps & MMC_MODE_HC) - cmd.cmdarg |= OCR_HCS; - - err = mmc_send_cmd(mmc, &cmd, NULL); - + err = mmc_send_op_cond_iter(mmc, &cmd, 1); if (err) return err; - - udelay(1000); - } while (!(cmd.response[0] & OCR_BUSY) && timeout--); - - if (timeout <= 0) - return UNUSABLE_ERR; + if (get_timer(start) > timeout) + return UNUSABLE_ERR; + udelay(100); + } while (!(mmc->op_cond_response & OCR_BUSY));

if (mmc_host_is_spi(mmc)) { /* read OCR for spi */ cmd.cmdidx = MMC_CMD_SPI_READ_OCR; @@ -1295,7 +1317,7 @@ block_dev_desc_t *mmc_get_dev(int dev) } #endif

-int mmc_init(struct mmc *mmc) +int mmc_start_init(struct mmc *mmc) { int err;

@@ -1335,17 +1357,48 @@ int mmc_init(struct mmc *mmc) if (err == TIMEOUT) { err = mmc_send_op_cond(mmc);

- if (err) { + if (err && err != IN_PROGRESS) { printf("Card did not respond to voltage select!\n"); return UNUSABLE_ERR; } }

- err = mmc_startup(mmc); + if (err == IN_PROGRESS) + mmc->init_in_progress = 1; + + return err; +} + +static int mmc_complete_init(struct mmc *mmc) +{ + int err = 0; + + if (mmc->op_cond_pending) + err = mmc_complete_op_cond(mmc); + + if (!err) + err = mmc_startup(mmc); if (err) mmc->has_init = 0; else mmc->has_init = 1; + mmc->init_in_progress = 0; + return err; +} + +int mmc_init(struct mmc *mmc) +{ + int err = IN_PROGRESS; + unsigned start = get_timer(0); + + if (mmc->has_init) + return 0; + if (!mmc->init_in_progress) + err = mmc_start_init(mmc); + + if (!err || err == IN_PROGRESS) + err = mmc_complete_init(mmc); + debug("%s: %d, time %lu\n", __func__, err, get_timer(start)); return err; }

@@ -1383,6 +1436,25 @@ int get_mmc_num(void) return cur_dev_num; }

+void mmc_set_preinit(struct mmc *mmc, int preinit) +{ + mmc->preinit = preinit; +} + +static void do_preinit(void) +{ + struct mmc *m; + struct list_head *entry; + + list_for_each(entry, &mmc_devices) { + m = list_entry(entry, struct mmc, link); + + if (m->preinit) + mmc_start_init(m); + } +} + + int mmc_initialize(bd_t *bis) { INIT_LIST_HEAD (&mmc_devices); @@ -1393,5 +1465,6 @@ int mmc_initialize(bd_t *bis)

print_mmc_devices(',');

+ do_preinit(); return 0; } diff --git a/include/mmc.h b/include/mmc.h index a13e2bd..445d714 100644 --- a/include/mmc.h +++ b/include/mmc.h @@ -62,6 +62,7 @@ #define UNUSABLE_ERR -17 /* Unusable Card */ #define COMM_ERR -18 /* Communications Error */ #define TIMEOUT -19 +#define IN_PROGRESS -20 /* operation is in progress */

#define MMC_CMD_GO_IDLE_STATE 0 #define MMC_CMD_SEND_OP_COND 1 @@ -260,6 +261,10 @@ struct mmc { int (*init)(struct mmc *mmc); int (*getcd)(struct mmc *mmc); uint b_max; + char op_cond_pending; /* 1 if we are waiting on an op_cond command */ + char init_in_progress; /* 1 if we have done mmc_start_init() */ + char preinit; /* start init as early as possible */ + uint op_cond_response; /* the response byte from the last op_cond */ };

int mmc_register(struct mmc *mmc); @@ -276,6 +281,31 @@ int mmc_switch_part(int dev_num, unsigned int part_num); int mmc_getcd(struct mmc *mmc); void spl_mmc_load(void) __noreturn;

+/** + * Start device initialization and return immediately; it does not block on + * polling OCR (operation condition register) status. Then you should call + * mmc_init, which would block on polling OCR status and complete the device + * initializatin. + * + * @param mmc Pointer to a MMC device struct + * @return 0 on success, IN_PROGRESS on waiting for OCR status, <0 on error. + */ +int mmc_start_init(struct mmc *mmc); + +/** + * Set preinit flag of mmc device. + * + * This will cause the device to be pre-inited during mmc_initialize(), + * which may save boot time if the device is not accessed until later. + * Some eMMC devices take 200-300ms to init, but unfortunately they + * must be sent a series of commands to even get them to start preparing + * for operation. + * + * @param mmc Pointer to a MMC device struct + * @param preinit preinit flag value + */ +void mmc_set_preinit(struct mmc *mmc, int preinit); + #ifdef CONFIG_GENERIC_MMC #define mmc_host_is_spi(mmc) ((mmc)->host_caps & MMC_MODE_SPI) struct mmc *mmc_spi_init(uint bus, uint cs, uint speed, uint mode);