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

[Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>]

Hi,

Maybe you have any comments or remarks about this patch? And if you don't could you please apply it. 

Thanks!

On Tue, 2017-09-26 at 16:10 +0300, Eugeniy Paltsev 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@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;
> +
> +	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();
> +
> +	if (!priv->bus_clk_rate)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
>  static int dw_spi_probe(struct udevice *bus)
>  {
>  	struct dw_spi_platdata *plat = dev_get_platdata(bus);
>  	struct dw_spi_priv *priv = dev_get_priv(bus);
> +	int ret;
>  
>  	priv->regs = plat->regs;
>  	priv->freq = plat->frequency;
>  
> +	ret = dw_spi_get_clk(bus);
> +	if (ret)
> +		return ret;
> +
>  	/* Currently only bits_per_word == 8 supported */
>  	priv->bits_per_word = 8;
>  
> @@ -369,7 +435,7 @@ static int dw_spi_set_speed(struct udevice *bus, uint speed)
>  	spi_enable_chip(priv, 0);
>  
>  	/* clk_div doesn't support odd number */
> -	clk_div = cm_get_spi_controller_clk_hz() / speed;
> +	clk_div = priv->bus_clk_rate / speed;
>  	clk_div = (clk_div + 1) & 0xfffe;
>  	dw_writel(priv, DW_SPI_BAUDR, clk_div);
>  
-- 
 Eugeniy Paltsev