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

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Message-Id: <20201106022726.19831-3-takahiro.akashi@linaro.org>
Date:   Fri,  6 Nov 2020 11:27:01 +0900
From:   AKASHI Takahiro <takahiro.akashi@...aro.org>
To:     ulf.hansson@...aro.org, adrian.hunter@...el.com
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        ben.chuang@...esyslogic.com.tw, greg.tu@...esyslogic.com.tw,
        AKASHI Takahiro <takahiro.akashi@...aro.org>
Subject: [RFC PATCH v3.1 02/27] mmc: core: UHS-II support, modify power-up sequence

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@...esyslogic.com.tw>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.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