linux-kernel - [PATCH V9 2/5] mmc: sdhci: Add PLL Enable support to internal clock setup

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Date:   Wed, 11 Sep 2019 15:23:01 +0800
From:   Ben Chuang <benchuanggli@...il.com>
To:     adrian.hunter@...el.com, ulf.hansson@...aro.org
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        johnsonm@...lj.org, ben.chuang@...esyslogic.com.tw,
        Ben Chuang <benchuanggli@...il.com>
Subject: [PATCH V9 2/5] mmc: sdhci: Add PLL Enable support to internal clock setup

From: Ben Chuang <ben.chuang@...esyslogic.com.tw>

The GL9750 and GL9755 chipsets, and possibly others, require PLL Enable
setup as part of the internal clock setup as described in 3.2.1 Internal
Clock Setup Sequence of SD Host Controller Simplified Specification
Version 4.20.

Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
Co-developed-by: Michael K Johnson <johnsonm@...lj.org>
Signed-off-by: Michael K Johnson <johnsonm@...lj.org>
Acked-by: Adrian Hunter <adrian.hunter@...el.com>
---
 drivers/mmc/host/sdhci.c | 23 +++++++++++++++++++++++
 drivers/mmc/host/sdhci.h |  1 +
 2 files changed, 24 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index bed0760a6c2a..9106ebc7a422 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1653,6 +1653,29 @@ void sdhci_enable_clk(struct sdhci_host *host, u16 clk)
 		udelay(10);
 	}
 
+	if (host->version >= SDHCI_SPEC_410 && host->v4_mode) {
+		clk |= SDHCI_CLOCK_PLL_EN;
+		clk &= ~SDHCI_CLOCK_INT_STABLE;
+		sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+		/* Wait max 150 ms */
+		timeout = ktime_add_ms(ktime_get(), 150);
+		while (1) {
+			bool timedout = ktime_after(ktime_get(), timeout);
+
+			clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+			if (clk & SDHCI_CLOCK_INT_STABLE)
+				break;
+			if (timedout) {
+				pr_err("%s: PLL clock never stabilised.\n",
+				       mmc_hostname(host->mmc));
+				sdhci_dumpregs(host);
+				return;
+			}
+			udelay(10);
+		}
+	}
+
 	clk |= SDHCI_CLOCK_CARD_EN;
 	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
 }
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 199712e7adbb..72601a4d2e95 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -114,6 +114,7 @@
 #define  SDHCI_DIV_HI_MASK	0x300
 #define  SDHCI_PROG_CLOCK_MODE	0x0020
 #define  SDHCI_CLOCK_CARD_EN	0x0004
+#define  SDHCI_CLOCK_PLL_EN	0x0008
 #define  SDHCI_CLOCK_INT_STABLE	0x0002
 #define  SDHCI_CLOCK_INT_EN	0x0001
 
-- 
2.23.0