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

[Jisheng Zhang]

+ DT maintainers

On Thu, 28 Sep 2017 17:05:20 +0200 Gregory CLEMENT wrote:

> 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 at vger.kernel.org>
> Signed-off-by: Gregory CLEMENT <gregory.clement at 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".

Is "bus" more suitable?

>  
>  - 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);

Since the bus clock is optional, can we remove this err msg?

> +		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() will do the check. So this check could be removed
to simplify the err path

> +		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);

ditto

>  
>  	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;
>  	/*