[PATCH] mmc: sdhci-xenon: Fix clock resource by adding an optional bus clock

[Gregory CLEMENT <gregory.clement@free-electrons.com>]

On Armada 7K/8K we need to explicitly enable the bus clock. The bus clock
is optional because not all the SoCs need them but at least for Armada
7K/8K it is actually mandatory.

The binding documentation is updating accordingly.

Without this patch the kernel hand during boot if the mvpp2.2 network
driver was not present in the kernel. Indeed the clock needed by the
xenon controller was set by the network driver.

Fixes: 3a3748dba881 ("mmc: sdhci-xenon: Add Marvell Xenon SDHC core
functionality)"
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
---
Hi Ulf and Adrian,

This patch should be merged in 4.14-rc, as it fixes real issues.

This patch maye looks like just as a nice clean-up but it is not. On
the earlier version of the series adding the support for the xenon
controller there was already this axi bus clock. But at this moment
the documentation for the clock on the Armada 7K/8K was missing and
there was no driver for it, so we just use the clock set by the
bootloader and never change them that's why it worked without any
visible problem.

Then as explained in the commit log the network driver enabled the
clock for us, and it happened that it was setup before the xenon
driver. It is only thanks the new information we received on the
clocks of the Sov and with more exhaustive testes that we found this
issue and the fix for it.

Thanks,

Gregory


 .../bindings/mmc/marvell,xenon-sdhci.txt           | 12 ++++++-----
 drivers/mmc/host/sdhci-xenon.c                     | 25 +++++++++++++++++++---
 drivers/mmc/host/sdhci-xenon.h                     |  1 +
 3 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt b/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
index b878a1e305af..6f3db1f809ab 100644
--- a/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
+++ b/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
@@ -16,11 +16,13 @@ Required Properties:
 
 - clocks:
   Array of clocks required for SDHC.
-  Require at least input clock for Xenon IP core.
+  Require at least input clock for Xenon IP core. For Armada AP806 and
+  CP110, the AXI clock is also mandatory.
 
 - clock-names:
   Array of names corresponding to clocks property.
   The input clock for Xenon IP core should be named as "core".
+  The input clock for the AXI bus must be named as "axi".
 
 - reg:
   * For "marvell,armada-3700-sdhci", two register areas.
@@ -106,8 +108,8 @@ Example:
 		compatible = "marvell,armada-ap806-sdhci";
 		reg = <0xaa0000 0x1000>;
 		interrupts = <GIC_SPI 13 IRQ_TYPE_LEVEL_HIGH>
-		clocks = <&emmc_clk>;
-		clock-names = "core";
+		clocks = <&emmc_clk>,<&axi_clk>;
+		clock-names = "core","axi";
 		bus-width = <4>;
 		marvell,xenon-phy-slow-mode;
 		marvell,xenon-tun-count = <11>;
@@ -126,8 +128,8 @@ Example:
 		interrupts = <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>
 		vqmmc-supply = <&sd_vqmmc_regulator>;
 		vmmc-supply = <&sd_vmmc_regulator>;
-		clocks = <&sdclk>;
-		clock-names = "core";
+		clocks = <&sdclk>,<&axi_clk>;
+		clock-names = "core","axi";
 		bus-width = <4>;
 		marvell,xenon-tun-count = <9>;
 	};
diff --git a/drivers/mmc/host/sdhci-xenon.c b/drivers/mmc/host/sdhci-xenon.c
index 2eec2e652c53..845575593b59 100644
--- a/drivers/mmc/host/sdhci-xenon.c
+++ b/drivers/mmc/host/sdhci-xenon.c
@@ -466,6 +466,7 @@ static int xenon_probe(struct platform_device *pdev)
 {
 	struct sdhci_pltfm_host *pltfm_host;
 	struct sdhci_host *host;
+	struct xenon_priv *priv;
 	int err;
 
 	host = sdhci_pltfm_init(pdev, &sdhci_xenon_pdata,
@@ -474,6 +475,7 @@ static int xenon_probe(struct platform_device *pdev)
 		return PTR_ERR(host);
 
 	pltfm_host = sdhci_priv(host);
+	priv = sdhci_pltfm_priv(pltfm_host);
 
 	/*
 	 * Link Xenon specific mmc_host_ops function,
@@ -491,9 +493,20 @@ static int xenon_probe(struct platform_device *pdev)
 	if (err)
 		goto free_pltfm;
 
+	priv->axi_clk = devm_clk_get(&pdev->dev, "axi");
+	if (IS_ERR(priv->axi_clk)) {
+		err = PTR_ERR(priv->axi_clk);
+		dev_err(&pdev->dev, "Failed to setup axi clk: %d\n", err);
+		priv->axi_clk = NULL;
+	} else {
+		err = clk_prepare_enable(priv->axi_clk);
+		if (err)
+			goto err_clk;
+	}
+
 	err = mmc_of_parse(host->mmc);
 	if (err)
-		goto err_clk;
+		goto err_clk_axi;
 
 	sdhci_get_of_property(pdev);
 
@@ -502,11 +515,11 @@ static int xenon_probe(struct platform_device *pdev)
 	/* Xenon specific dt parse */
 	err = xenon_probe_dt(pdev);
 	if (err)
-		goto err_clk;
+		goto err_clk_axi;
 
 	err = xenon_sdhc_prepare(host);
 	if (err)
-		goto err_clk;
+		goto err_clk_axi;
 
 	pm_runtime_get_noresume(&pdev->dev);
 	pm_runtime_set_active(&pdev->dev);
@@ -527,6 +540,9 @@ static int xenon_probe(struct platform_device *pdev)
 	pm_runtime_disable(&pdev->dev);
 	pm_runtime_put_noidle(&pdev->dev);
 	xenon_sdhc_unprepare(host);
+err_clk_axi:
+	if (priv->axi_clk)
+		clk_disable_unprepare(priv->axi_clk);
 err_clk:
 	clk_disable_unprepare(pltfm_host->clk);
 free_pltfm:
@@ -538,6 +554,7 @@ static int xenon_remove(struct platform_device *pdev)
 {
 	struct sdhci_host *host = platform_get_drvdata(pdev);
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct xenon_priv *priv = sdhci_pltfm_priv(pltfm_host);
 
 	pm_runtime_get_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
@@ -546,6 +563,8 @@ static int xenon_remove(struct platform_device *pdev)
 	sdhci_remove_host(host, 0);
 
 	xenon_sdhc_unprepare(host);
+	if (priv->axi_clk)
+		clk_disable_unprepare(priv->axi_clk);
 
 	clk_disable_unprepare(pltfm_host->clk);
 
diff --git a/drivers/mmc/host/sdhci-xenon.h b/drivers/mmc/host/sdhci-xenon.h
index 2bc0510c0769..9994995c7c56 100644
--- a/drivers/mmc/host/sdhci-xenon.h
+++ b/drivers/mmc/host/sdhci-xenon.h
@@ -83,6 +83,7 @@ struct xenon_priv {
 	unsigned char	bus_width;
 	unsigned char	timing;
 	unsigned int	clock;
+	struct clk      *axi_clk;
 
 	int		phy_type;
 	/*
-- 
2.14.1