Re: [PATCH 2/2] mmc: dw_mmc: Add the ability to set the ciu clock frequency

Jaehoon Chung
2013-06-07T05:35:47Z

Looks good to me. If you can add the usage example, it will be more helpful to me.

Acked-by: Jaehoon Chung <jh80.chung@samsung.com>

On 06/07/2013 01:46 PM, Doug Anderson wrote:
> As of now we rely on code outside of the driver to set the ciu clock
> frequency. There's no reason to do that. Add support for setting up
> the clock in the driver during probe.
>
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> ---
> .../devicetree/bindings/mmc/synopsis-dw-mshc.txt | 13 +++++++++++++
> drivers/mmc/host/dw_mmc.c | 17 +++++++++++++----
> 2 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt
> index b09d2d0..edb7659 100644
> --- a/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt
> +++ b/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt
> @@ -39,6 +39,19 @@ Required Properties:
>
> Optional properties:
>
> +* clocks: from common clock binding: handle to biu and ciu clocks for the
> + bus interface unit clock and the card interface unit clock.
> +
> +* clock-names: from common clock binding: Shall be "biu" and "ciu".
> + If the biu clock is missing we'll simply skip enabling it. If the
> + ciu clock is missing we'll just assume that the clock is running at
> + clock-frequency. It is an error to omit both the ciu clock and the
> + clock-frequency.
> +
> +* clock-frequency: should be the frequency (in Hz) of the ciu clock. If this
> + is specified and the ciu clock is specified then we'll try to set the ciu
> + clock to this at probe time.
> +
> * num-slots: specifies the number of slots supported by the controller.
> The number of physical slots actually used could be equal or less than the
> value specified by num-slots. If this property is not specified, the value
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index d3a0f8a..7ffb502 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -2133,6 +2133,7 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
> struct device_node *np = dev->of_node;
> const struct dw_mci_drv_data *drv_data = host->drv_data;
> int idx, ret;
> + u32 clock_frequency;
>
> pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> if (!pdata) {
> @@ -2159,6 +2160,9 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
>
> of_property_read_u32(np, "card-detect-delay", &pdata->detect_delay_ms);
>
> + if (!of_property_read_u32(np, "clock-frequency", &clock_frequency))
> + pdata->bus_hz = clock_frequency;
> +
> if (drv_data && drv_data->parse_dt) {
> ret = drv_data->parse_dt(host);
> if (ret)
> @@ -2223,18 +2227,23 @@ int dw_mci_probe(struct dw_mci *host)
> host->ciu_clk = devm_clk_get(host->dev, "ciu");
> if (IS_ERR(host->ciu_clk)) {
> dev_dbg(host->dev, "ciu clock not available\n");
> + host->bus_hz = host->pdata->bus_hz;
> } else {
> ret = clk_prepare_enable(host->ciu_clk);
> if (ret) {
> dev_err(host->dev, "failed to enable ciu clock\n");
> goto err_clk_biu;
> }
> - }
>
> - if (IS_ERR(host->ciu_clk))
> - host->bus_hz = host->pdata->bus_hz;
> - else
> + if (host->pdata->bus_hz) {
> + ret = clk_set_rate(host->ciu_clk, host->pdata->bus_hz);
> + if (ret)
> + dev_warn(host->dev,
> + "Unable to set bus rate to %ul\n",
> + host->pdata->bus_hz);
> + }
> host->bus_hz = clk_get_rate(host->ciu_clk);
> + }
>
> if (drv_data && drv_data->setup_clock) {
> ret = drv_data->setup_clock(host);
>