Re: [PATCH v2 2/3] spi: meson-axg: enhance output enable feature

From: Jerome Brunet
Date: Thu Dec 13 2018 - 04:05:03 EST


On Thu, 2018-12-13 at 16:39 +0800, Sunny Luo wrote:
> The SPICC controller in Meson-AXG is capable of driving the CLK/MOSI/SS
> signal lines through the idle state (between two transmission operation),
> which avoid the signals floating in unexpected state.
>
> Signed-off-by: Sunny Luo <sunny.luo@xxxxxxxxxxx>
> Signed-off-by: Yixun Lan <yixun.lan@xxxxxxxxxxx>
> ---
> drivers/spi/spi-meson-spicc.c | 28 ++++++++++++++++++++++++++--
> 1 file changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
> index b56249d..0384c28 100644
> --- a/drivers/spi/spi-meson-spicc.c
> +++ b/drivers/spi/spi-meson-spicc.c
> @@ -115,6 +115,13 @@
>
> #define SPICC_DWADDR 0x24 /* Write Address of DMA */
>
> +#define SPICC_ENH_CTL0 0x38 /* Enhanced Feature */
> +#define SPICC_ENH_MOSI_OEN BIT(25)
> +#define SPICC_ENH_CLK_OEN BIT(26)
> +#define SPICC_ENH_CS_OEN BIT(27)
> +#define SPICC_ENH_CLK_CS_DELAY_EN BIT(28)
> +#define SPICC_ENH_MAIN_CLK_AO BIT(29)
> +
> #define writel_bits_relaxed(mask, val, addr) \
> writel_relaxed((readl_relaxed(addr) & ~(mask)) | (val), addr)
>
> @@ -123,6 +130,7 @@
>
> struct meson_spicc_data {
> unsigned int max_speed_hz;
> + bool has_oen;
> };
>
> struct meson_spicc_device {
> @@ -145,6 +153,19 @@ struct meson_spicc_device {
> bool is_last_burst;
> };
>
> +static void meson_spicc_oen_enable(struct meson_spicc_device *spicc)
> +{
> + u32 conf;
> +
> + if (!spicc->data->has_oen)
> + return;
> +
> + conf = readl_relaxed(spicc->base + SPICC_ENH_CTL0) |
> + SPICC_ENH_MOSI_OEN | SPICC_ENH_CLK_OEN | SPICC_ENH_CS_OEN;
> +
> + writel_relaxed(conf, spicc->base + SPICC_ENH_CTL0);
> +}
> +
> static inline bool meson_spicc_txfull(struct meson_spicc_device *spicc)
> {
> return !!FIELD_GET(SPICC_TF,
> @@ -453,6 +474,8 @@ static int meson_spicc_prepare_message(struct spi_master
> *master,
>
> writel_bits_relaxed(BIT(24), BIT(24), spicc->base + SPICC_TESTREG);
>
> + meson_spicc_oen_enable(spicc);
> +

Any specific reason for doing this in prepare_message() ? It looks like
something that could/should be done during the probe ?

> return 0;
> }
>
> @@ -610,11 +633,12 @@ static int meson_spicc_remove(struct platform_device
> *pdev)
> }
>
> static const struct meson_spicc_data meson_spicc_gx_data = {
> - .max_speed_hz = 30000000,
> + .max_speed_hz = 30000000,
> };
>
> static const struct meson_spicc_data meson_spicc_axg_data = {
> - .max_speed_hz = 80000000,
> + .max_speed_hz = 80000000,
> + .has_oen = true,
> };
>
> static const struct of_device_id meson_spicc_of_match[] = {