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

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>
Tested-by: Zhoujie Wu <zjwu@marvell.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

3 files changed, 28 insertions, 9 deletions

diff --git a/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt b/Documentation/devicetree/bindings/mmc/marvell,xenon-sdhci.txt
index b878a1e305af..ed1456f5c94d 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..0842bbc2d7ad 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);
+                if (err == -EPROBE_DEFER)
+                        goto err_clk;
+        } 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 +540,8 @@ remove_sdhc:
         pm_runtime_disable(&pdev->dev);
         pm_runtime_put_noidle(&pdev->dev);
         xenon_sdhc_unprepare(host);
+err_clk_axi:
+        clk_disable_unprepare(priv->axi_clk);
 err_clk:
         clk_disable_unprepare(pltfm_host->clk);
 free_pltfm:
@@ -538,6 +553,7 @@ 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);
@@ -546,7 +562,7 @@ static int xenon_remove(struct platform_device *pdev)
         sdhci_remove_host(host, 0);
 
         xenon_sdhc_unprepare(host);
-
+        clk_disable_unprepare(priv->axi_clk);
         clk_disable_unprepare(pltfm_host->clk);
 
         sdhci_pltfm_free(pdev);
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;
         /*