[RFC PATCH v3.1 02/27] mmc: core: UHS-II support, modify power-up sequence

AKASHI Takahiro
2020-11-06T02:28:06Z

According to Fig. 3-35 in "SD Host Controller Simplified Spec. Ver4.20":
- Prepare vdd1, vdd2 and ios.timing for using after/in step (2)
- chip_select is not used in UHS-II, used to return to the legacy flow

Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
drivers/mmc/core/core.c | 61 +++++++++++++++++++++++++-----------
drivers/mmc/core/regulator.c | 14 +++++++++
2 files changed, 56 insertions(+), 19 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index d42037f0f10d..5541ed956c4d 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1315,33 +1315,52 @@ void mmc_power_up(struct mmc_host *host, u32 ocr)
if (host->ios.power_mode == MMC_POWER_ON)
return;

- mmc_pwrseq_pre_power_on(host);
+ if (host->flags & MMC_UHS2_SUPPORT) {
+ /* TODO: handle 'ocr' parameter */
+ host->ios.vdd = fls(host->ocr_avail) - 1;
+ host->ios.vdd2 = fls(host->ocr_avail_uhs2) - 1;
+ if (mmc_host_is_spi(host))
+ host->ios.chip_select = MMC_CS_HIGH;
+ else
+ host->ios.chip_select = MMC_CS_DONTCARE;
+ host->ios.timing = MMC_TIMING_UHS2;
+ } else {
+ mmc_pwrseq_pre_power_on(host);

- host->ios.vdd = fls(ocr) - 1;
- host->ios.power_mode = MMC_POWER_UP;
- /* Set initial state and call mmc_set_ios */
- mmc_set_initial_state(host);
+ host->ios.vdd = fls(ocr) - 1;
+ host->ios.power_mode = MMC_POWER_UP;
+ /* Set initial state and call mmc_set_ios */
+ mmc_set_initial_state(host);

- mmc_set_initial_signal_voltage(host);
+ mmc_set_initial_signal_voltage(host);

- /*
- * This delay should be sufficient to allow the power supply
- * to reach the minimum voltage.
- */
- mmc_delay(host->ios.power_delay_ms);
+ /*
+ * This delay should be sufficient to allow the power supply
+ * to reach the minimum voltage.
+ */
+ mmc_delay(host->ios.power_delay_ms);

- mmc_pwrseq_post_power_on(host);
+ mmc_pwrseq_post_power_on(host);

+ }
host->ios.clock = host->f_init;
-
host->ios.power_mode = MMC_POWER_ON;
+
mmc_set_ios(host);

- /*
- * This delay must be at least 74 clock sizes, or 1 ms, or the
- * time required to reach a stable voltage.
- */
- mmc_delay(host->ios.power_delay_ms);
+ if (host->flags & MMC_UHS2_SUPPORT)
+ /*
+ * This delay should be sufficient to allow the power supply
+ * to reach the minimum voltage.
+ */
+ /* TODO: avoid an immediate value */
+ mmc_delay(10);
+ else
+ /*
+ * This delay must be at least 74 clock sizes, or 1 ms, or the
+ * time required to reach a stable voltage.
+ */
+ mmc_delay(host->ios.power_delay_ms);
}

void mmc_power_off(struct mmc_host *host)
@@ -2316,7 +2335,11 @@ void mmc_start_host(struct mmc_host *host)

if (!(host->caps2 & MMC_CAP2_NO_PRESCAN_POWERUP)) {
mmc_claim_host(host);
- mmc_power_up(host, host->ocr_avail);
+
+ /* Power up here will make UHS2 init ugly. */
+ if (!(host->caps & MMC_CAP_UHS2))
+ mmc_power_up(host, host->ocr_avail);
+
mmc_release_host(host);
}

diff --git a/drivers/mmc/core/regulator.c b/drivers/mmc/core/regulator.c
index 609201a467ef..629e25bc8cb7 100644
--- a/drivers/mmc/core/regulator.c
+++ b/drivers/mmc/core/regulator.c
@@ -249,6 +249,7 @@ int mmc_regulator_get_supply(struct mmc_host *mmc)

mmc->supply.vmmc = devm_regulator_get_optional(dev, "vmmc");
mmc->supply.vqmmc = devm_regulator_get_optional(dev, "vqmmc");
+ mmc->supply.vmmc2 = devm_regulator_get_optional(dev, "vmmc2");

if (IS_ERR(mmc->supply.vmmc)) {
if (PTR_ERR(mmc->supply.vmmc) == -EPROBE_DEFER)
@@ -268,6 +269,19 @@ int mmc_regulator_get_supply(struct mmc_host *mmc)
dev_dbg(dev, "No vqmmc regulator found\n");
}

+ if (IS_ERR(mmc->supply.vmmc2)) {
+ if (PTR_ERR(mmc->supply.vmmc2) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+ dev_dbg(dev, "No vmmc2 regulator found\n");
+ } else {
+ ret = mmc_regulator_get_ocrmask(mmc->supply.vmmc2);
+ if (ret > 0)
+ mmc->ocr_avail_uhs2 = ret;
+ else
+ dev_warn(dev, "Failed getting UHS2 OCR mask: %d\n",
+ ret);
+ }
+
return 0;
}
EXPORT_SYMBOL_GPL(mmc_regulator_get_supply);
--
2.28.0