[U-Boot] [PATCH 2/2] SPI: mxc_spi: delay initialisation until claim bus

[Jagan Teki]

On 1 September 2014 14:16, Markus Niebel <list-09_u-boot at tqsc.de> wrote:
> From: Markus Niebel <Markus.Niebel at tq-group.com>
>
> it is not correct to init for a specific slave in spi_setup_slave.
> instead buffer the values and delay init until spi_claim_bus.
>
> Signed-off-by: Markus Niebel <Markus.Niebel at tq-group.com>
> ---
>  drivers/spi/mxc_spi.c | 37 +++++++++++++++++++++----------------
>  1 file changed, 21 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c
> index 6a05d15..c741738 100644
> --- a/drivers/spi/mxc_spi.c
> +++ b/drivers/spi/mxc_spi.c
> @@ -43,6 +43,8 @@ struct mxc_spi_slave {
>  #endif
>         int             gpio;
>         int             ss_pol;
> +       unsigned int    max_hz;
> +       unsigned int    mode;
>  };
>
>  static inline struct mxc_spi_slave *to_mxc_spi_slave(struct spi_slave *slave)
> @@ -77,12 +79,13 @@ u32 get_cspi_div(u32 div)
>  }
>
>  #ifdef MXC_CSPI
> -static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs,
> -               unsigned int max_hz, unsigned int mode)
> +static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs)
>  {
>         unsigned int ctrl_reg;
>         u32 clk_src;
>         u32 div;
> +       unsigned int max_hz = mxcs->max_hz;
> +       unsigned int mode = mxcs->mode;
>
>         clk_src = mxc_get_clock(MXC_CSPI_CLK);
>
> @@ -114,19 +117,15 @@ static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs,
>  #endif
>
>  #ifdef MXC_ECSPI
> -static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs,
> -               unsigned int max_hz, unsigned int mode)
> +static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs)
>  {
>         u32 clk_src = mxc_get_clock(MXC_CSPI_CLK);
>         s32 reg_ctrl, reg_config;
>         u32 ss_pol = 0, sclkpol = 0, sclkpha = 0, sclkctl = 0;
>         u32 pre_div = 0, post_div = 0;
>         struct cspi_regs *regs = (struct cspi_regs *)mxcs->base;
> -
> -       if (max_hz == 0) {
> -               printf("Error: desired clock is 0\n");
> -               return -1;
> -       }
> +       unsigned int max_hz = mxcs->max_hz;
> +       unsigned int mode = mxcs->mode;
>
>         /*
>          * Reset SPI and set all CSs to master mode, if toggling
> @@ -404,6 +403,11 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
>         if (bus >= ARRAY_SIZE(spi_bases))
>                 return NULL;
>
> +       if (max_hz == 0) {
> +               printf("Error: desired clock is 0\n");
> +               return NULL;
> +       }
> +
>         mxcs = spi_alloc_slave(struct mxc_spi_slave, bus, cs);
>         if (!mxcs) {
>                 puts("mxc_spi: SPI Slave not allocated !\n");
> @@ -421,13 +425,9 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
>         cs = ret;
>
>         mxcs->base = spi_bases[bus];
> +       mxcs->max_hz = max_hz;
> +       mxcs->mode = mode;
>
> -       ret = spi_cfg_mxc(mxcs, cs, max_hz, mode);
> -       if (ret) {
> -               printf("mxc_spi: cannot setup SPI controller\n");
> -               free(mxcs);
> -               return NULL;
> -       }
>         return &mxcs->slave;
>  }
>
> @@ -440,12 +440,17 @@ void spi_free_slave(struct spi_slave *slave)
>
>  int spi_claim_bus(struct spi_slave *slave)
>  {
> +       int ret;
>         struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
>         struct cspi_regs *regs = (struct cspi_regs *)mxcs->base;
>
>         reg_write(&regs->rxdata, 1);
>         udelay(1);
> -       reg_write(&regs->ctrl, mxcs->ctrl_reg);
> +       ret = spi_cfg_mxc(mxcs, slave->cs);
> +       if (ret) {
> +               printf("mxc_spi: cannot setup SPI controller\n");
> +               return ret;
> +       }
>         reg_write(&regs->period, MXC_CSPIPERIOD_32KHZ);
>         reg_write(&regs->intr, 0);
>
> --
> 2.1.0
>

In fact this driver is using spi_cfg_mxc() for configuring SPI
clock,polarities and frequency
in spi_setup_slave() time, but usually spi_setup_slave() will require
only basic controller reg
initialization. So while in spi_claim_bus() clock, polarities and
frequencies will handle.

Please think on that direction and will be good if you fix those and
send the patches for next time.

thanks!
-- 
Jagan.