Re: [PATCH v3 3/9] mmc: sdhci-msm: add pltfm_data support to get clk-rates from DT

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Thu 18 Aug 21:36 PDT 2016, Ritesh Harjani wrote:

> This adds support for sdhc-msm controllers to get supported
> clk-rates from DT. sdhci-msm would need it's own set_clock
> ops to be implemented. For this, supported clk-rates needs
> to be populated in sdhci_msm_pltfm_data.
> 
> Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
> ---
>  .../devicetree/bindings/mmc/sdhci-msm.txt          |  1 +
>  drivers/mmc/host/sdhci-msm.c                       | 71 ++++++++++++++++++++++
>  2 files changed, 72 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
> index 485483a..6a83b38 100644
> --- a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
> +++ b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
> @@ -17,6 +17,7 @@ Required properties:
>  	"iface" - Main peripheral bus clock (PCLK/HCLK - AHB Bus clock) (required)
>  	"core"	- SDC MMC clock (MCLK) (required)
>  	"bus"	- SDCC bus voter clock (optional)
> +- clk-rates: Array of supported GCC clock frequencies for sdhc, Units - Hz.
>  
>  Example:
>  
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 85ddaae..2bf141b 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -74,6 +74,11 @@
>  #define CMUX_SHIFT_PHASE_SHIFT	24
>  #define CMUX_SHIFT_PHASE_MASK	(7 << CMUX_SHIFT_PHASE_SHIFT)
>  
> +struct sdhci_msm_pltfm_data {
> +	u32 *clk_table;
> +	size_t clk_table_sz;
> +};

Rather than calling this "platform data", just call it
sdhci_msm_freq_table and make it:

struct sdhci_msm_freq_table {
	size_t num_freqs;
	u32 freqs[];
};

> +
>  struct sdhci_msm_host {
>  	struct platform_device *pdev;
>  	void __iomem *core_mem;	/* MSM SDCC mapped address */
> @@ -83,6 +88,7 @@ struct sdhci_msm_host {
>  	struct clk *bus_clk;	/* SDHC bus voter clock */
>  	struct mmc_host *mmc;
>  	bool use_14lpp_dll_reset;
> +	struct sdhci_msm_pltfm_data *pdata;
>  };
>  
>  /* Platform specific tuning */
> @@ -582,6 +588,67 @@ static const struct sdhci_pltfm_data sdhci_msm_pdata = {
>  	.ops = &sdhci_msm_ops,
>  };
>  
> +static int sdhci_msm_dt_get_array(struct device *dev, const char *prop_name,
> +				u32 **table, size_t *size)
> +{
> +	struct device_node *np = dev->of_node;
> +	int count = 0;
> +	u32 *arr = NULL;
> +	int ret = 0;
> +
> +	count = of_property_count_elems_of_size(np, prop_name, sizeof(u32));
> +	if (count < 0) {
> +		dev_err(dev, "%s: Invalid dt property, err(%d)\n",
> +				prop_name, count);
> +		ret = count;
> +		goto out;
> +	}
> +
> +	arr = devm_kzalloc(dev, count * sizeof(*arr), GFP_KERNEL);
> +	if (!arr) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	ret = of_property_read_u32_array(np, prop_name, arr, count);
> +	if (ret) {
> +		dev_err(dev, "%s Invalid dt array property, err(%d)\n",
> +				prop_name, ret);
> +		goto out;
> +	}
> +	*table = arr;
> +	*size = count;
> +out:
> +	return ret;
> +}
> +
> +static struct sdhci_msm_pltfm_data *sdhci_msm_populate_pdata(struct device *dev,
> +						struct sdhci_msm_host *msm_host)
> +{
> +	struct sdhci_msm_pltfm_data *pdata = NULL;
> +	size_t table_sz = 0;
> +	u32 *table = NULL;
> +

Count of_property_count_elems_of_size() here and then allocate
sizeof(*tbl) + count * sizeof(tbl->freqs[0]) and fill that in, no need
for the two allocations.

> +	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> +	if (!pdata)
> +		goto out;

No need for a goto for early errors, just return as you haven't touch
any state yet.

> +
> +	if (sdhci_msm_dt_get_array(dev, "clk-rates", &table, &table_sz)) {
> +		dev_err(dev, "failed in DT parsing for supported clk-rates\n");
> +		goto out;
> +	}
> +	if (!table || !table_sz) {

A general comment; don't be too defensive in your code. Neither table
nor table_sz should be able to be zero if the above condition fails...

> +		dev_err(dev, "Invalid clock table\n");
> +		goto out;
> +	}
> +	pdata->clk_table = table;
> +	pdata->clk_table_sz = table_sz;
> +
> +	return pdata;
> +out:
> +	return NULL;
> +}
> +
>  static int sdhci_msm_probe(struct platform_device *pdev)
>  {
>  	struct sdhci_host *host;
> @@ -608,6 +675,10 @@ static int sdhci_msm_probe(struct platform_device *pdev)
>  
>  	sdhci_get_of_property(pdev);
>  
> +	msm_host->pdata = sdhci_msm_populate_pdata(&pdev->dev, msm_host);
> +	if (!msm_host->pdata)
> +		goto pltfm_free;

Adding this as a requirement breaks existing platforms/dtbs, you may
force it for 8996 if you can detect that, but you should not change it
for existing platforms.

> +
>  	/* Setup SDCC bus voter clock. */
>  	msm_host->bus_clk = devm_clk_get(&pdev->dev, "bus");
>  	if (!IS_ERR(msm_host->bus_clk)) {

Regards,
Bjorn