linux-kernel - [PATCH V2 8/9] mmc: mmci: sdmmc: add voltage switch functions

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Message-ID: <20200128090636.13689-9-ludovic.barre@st.com>
Date:   Tue, 28 Jan 2020 10:06:35 +0100
From:   Ludovic Barre <ludovic.barre@...com>
To:     Ulf Hansson <ulf.hansson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>
CC:     <srinivas.kandagatla@...aro.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-mmc@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        Ludovic Barre <ludovic.barre@...com>
Subject: [PATCH V2 8/9] mmc: mmci: sdmmc: add voltage switch functions

To prepare the voltage switch procedure, the VSWITCHEN bit must be
set before sending the cmd11.
To confirm completion of voltage switch, the VSWEND flag must be
checked.

Signed-off-by: Ludovic Barre <ludovic.barre@...com>
---
 drivers/mmc/host/mmci.h             |  4 +++
 drivers/mmc/host/mmci_stm32_sdmmc.c | 43 +++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index c3bc0a38d4cb..e1a9b96a3396 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -165,6 +165,7 @@
 /* Extended status bits for the STM32 variants */
 #define MCI_STM32_BUSYD0	BIT(20)
 #define MCI_STM32_BUSYD0END	BIT(21)
+#define MCI_STM32_VSWEND	BIT(25)
 
 #define MMCICLEAR		0x038
 #define MCI_CMDCRCFAILCLR	(1 << 0)
@@ -182,6 +183,9 @@
 #define MCI_ST_SDIOITC		(1 << 22)
 #define MCI_ST_CEATAENDC	(1 << 23)
 #define MCI_ST_BUSYENDC		(1 << 24)
+/* Extended clear bits for the STM32 variants */
+#define MCI_STM32_VSWENDC	BIT(25)
+#define MCI_STM32_CKSTOPC	BIT(26)
 
 #define MMCIMASK0		0x03c
 #define MCI_CMDCRCFAILMASK	(1 << 0)
diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
index fa875febcc85..f76e82f8f12f 100644
--- a/drivers/mmc/host/mmci_stm32_sdmmc.c
+++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
@@ -32,6 +32,7 @@
 #define DLYB_CFGR_UNIT_MAX	127
 
 #define DLYB_LNG_TIMEOUT_US	1000
+#define SDMMC_VSWEND_TIMEOUT_US 10000
 
 struct sdmmc_lli_desc {
 	u32 idmalar;
@@ -265,6 +266,7 @@ static void mmci_sdmmc_set_pwrreg(struct mmci_host *host, unsigned int pwr)
 	struct mmc_ios ios = host->mmc->ios;
 	struct sdmmc_dlyb *dlyb = host->variant_priv;
 
+	/* adds OF options */
 	pwr = host->pwr_reg_add;
 
 	sdmmc_dlyb_input_ck(dlyb);
@@ -291,6 +293,10 @@ static void mmci_sdmmc_set_pwrreg(struct mmci_host *host, unsigned int pwr)
 		writel(MCI_IRQENABLE | host->variant->start_err,
 		       host->base + MMCIMASK0);
 
+		/* preserves voltage switch bits */
+		pwr |= host->pwr_reg & (MCI_STM32_VSWITCHEN |
+					MCI_STM32_VSWITCH);
+
 		/*
 		 * After a power-cycle state, we must set the SDMMC in
 		 * Power-off. The SDMMC_D[7:0], SDMMC_CMD and SDMMC_CK are
@@ -456,6 +462,41 @@ static int sdmmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	return sdmmc_dlyb_phase_tuning(host, opcode);
 }
 
+static void sdmmc_pre_sig_volt_vswitch(struct mmci_host *host)
+{
+	/* clear the voltage switch completion flag */
+	writel_relaxed(MCI_STM32_VSWENDC, host->base + MMCICLEAR);
+	/* enable Voltage switch procedure */
+	mmci_write_pwrreg(host, host->pwr_reg | MCI_STM32_VSWITCHEN);
+}
+
+static int sdmmc_post_sig_volt_switch(struct mmci_host *host,
+				      struct mmc_ios *ios)
+{
+	unsigned long flags;
+	u32 status;
+	int ret = 0;
+
+	if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180) {
+		spin_lock_irqsave(&host->lock, flags);
+		mmci_write_pwrreg(host, host->pwr_reg | MCI_STM32_VSWITCH);
+		spin_unlock_irqrestore(&host->lock, flags);
+
+		/* wait voltage switch completion while 10ms */
+		ret = readl_relaxed_poll_timeout(host->base + MMCISTATUS,
+						 status,
+						 (status & MCI_STM32_VSWEND),
+						 10, SDMMC_VSWEND_TIMEOUT_US);
+
+		writel_relaxed(MCI_STM32_VSWENDC | MCI_STM32_CKSTOPC,
+			       host->base + MMCICLEAR);
+		mmci_write_pwrreg(host, host->pwr_reg &
+				  ~(MCI_STM32_VSWITCHEN | MCI_STM32_VSWITCH));
+	}
+
+	return ret;
+}
+
 static struct mmci_host_ops sdmmc_variant_ops = {
 	.validate_data = sdmmc_idma_validate_data,
 	.prep_data = sdmmc_idma_prep_data,
@@ -467,6 +508,8 @@ static struct mmci_host_ops sdmmc_variant_ops = {
 	.set_clkreg = mmci_sdmmc_set_clkreg,
 	.set_pwrreg = mmci_sdmmc_set_pwrreg,
 	.busy_complete = sdmmc_busy_complete,
+	.pre_sig_volt_switch = sdmmc_pre_sig_volt_vswitch,
+	.post_sig_volt_switch = sdmmc_post_sig_volt_switch,
 };
 
 void sdmmc_variant_init(struct mmci_host *host)
-- 
2.17.1