[U-Boot] [PATCH RESEND] DW SPI: Get clock value from Device Tree

[Jagan Teki]

On Tue, Sep 26, 2017 at 6:40 PM, Eugeniy Paltsev
<Eugeniy.Paltsev at synopsys.com> wrote:
> Add option to set spi controller clock frequency via device tree
> using standard clock bindings.
> Old way of setting spi controller clock frequency (via implementation
> of 'cm_get_spi_controller_clk_hz' function in platform specific code)
> remains supported.
>
> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev at synopsys.com>
> ---
>  Resending due to previously sent one was discarded by mailing list.
>
>  drivers/spi/designware_spi.c | 68 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 67 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c
> index 5aa507b..c70697e 100644
> --- a/drivers/spi/designware_spi.c
> +++ b/drivers/spi/designware_spi.c
> @@ -11,6 +11,7 @@
>   */
>
>  #include <common.h>
> +#include <clk.h>
>  #include <dm.h>
>  #include <errno.h>
>  #include <malloc.h>
> @@ -94,6 +95,7 @@ struct dw_spi_priv {
>         void __iomem *regs;
>         unsigned int freq;              /* Default frequency */
>         unsigned int mode;
> +       unsigned long bus_clk_rate;
>
>         int bits_per_word;
>         u8 cs;                  /* chip select pin */
> @@ -176,14 +178,78 @@ static void spi_hw_init(struct dw_spi_priv *priv)
>         debug("%s: fifo_len=%d\n", __func__, priv->fifo_len);
>  }
>
> +/*
> + * cm_get_spi_controller_clk_hz function is old way to set spi controller
> + * frequency. If it isn't implemented and spi controller frequency isn't set via
> + * device tree we will get into next default function.
> + */
> +__weak unsigned int cm_get_spi_controller_clk_hz(void)
> +{
> +       error("SPI clock is defined neither via device tree nor via cm_get_spi_controller_clk_hz!");
> +
> +       return 0;
> +}
> +
> +static int dw_spi_of_get_clk(struct udevice *bus)
> +{
> +#if CONFIG_IS_ENABLED(OF_CONTROL) && CONFIG_IS_ENABLED(CLK)
> +       struct dw_spi_priv *priv = dev_get_priv(bus);
> +       unsigned long clk_rate;
> +       struct clk clk;
> +       int ret;
> +
> +       ret = clk_get_by_index(bus, 0, &clk);
> +       if (ret)
> +               return -EINVAL;
> +
> +       ret = clk_enable(&clk);
> +       if (ret && ret != -ENOSYS)
> +               return ret;
> +
> +       clk_rate = clk_get_rate(&clk);
> +       if (!clk_rate)
> +               return -EINVAL;

Use bus_clk_rate instead of local clk_rate and disable the clk if it
can't get the rate.

> +
> +       priv->bus_clk_rate = clk_rate;
> +
> +       clk_free(&clk);
> +
> +       return 0;
> +#endif
> +
> +       return -ENOSYS;
> +}
> +
> +static int dw_spi_get_clk(struct udevice *bus)
> +{
> +       struct dw_spi_priv *priv = dev_get_priv(bus);
> +
> +       /* Firstly try to get clock frequency from device tree */
> +       if (!dw_spi_of_get_clk(bus))
> +               return 0;
> +
> +       /* In case of failure rollback to cm_get_spi_controller_clk_hz */
> +       priv->bus_clk_rate = cm_get_spi_controller_clk_hz();

Why weak function, we can just return with error message since weak
does the same job

thanks!
-- 
Jagan Teki
Free Software Engineer | www.openedev.com
U-Boot, Linux | Upstream Maintainer
Hyderabad, India.