[PATCH] spi-imx: Add loopback mode support

[PATCH] spi-imx: Add loopback mode support

[Fabio Estevam]

From: Fabio Estevam <fabio.estevam-KZfg59tc24xl57MIdRCFDg@public.gmane.org>

Loopback mode can be activated by setting bit LBC (LoopBack
Control) of register ECSPI_TESTREG.

Add support for it.

Signed-off-by: Fabio Estevam <fabio.estevam-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
---
 drivers/spi/spi-imx.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 0e5723a..e7e4f0c 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -244,6 +244,9 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
 #define MX51_ECSPI_STAT		0x18
 #define MX51_ECSPI_STAT_RR		(1 <<  3)
 
+#define MX51_ECSPI_TESTREG	0x20
+#define MX51_ECSPI_TESTREG_LBC	BIT(31)
+
 /* MX51 eCSPI */
 static unsigned int mx51_ecspi_clkdiv(unsigned int fin, unsigned int fspi,
 				      unsigned int *fres)
@@ -313,7 +316,7 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
 {
 	u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0, dma = 0;
 	u32 tx_wml_cfg, rx_wml_cfg, rxt_wml_cfg;
-	u32 clk = config->speed_hz, delay;
+	u32 clk = config->speed_hz, delay, reg;
 
 	/*
 	 * The hardware seems to have a race condition when changing modes. The
@@ -351,6 +354,13 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
 	else
 		cfg &= ~MX51_ECSPI_CONFIG_SSBPOL(config->cs);
 
+	reg = readl(spi_imx->base + MX51_ECSPI_TESTREG);
+	if (config->mode & SPI_LOOP)
+		reg |= MX51_ECSPI_TESTREG_LBC;
+	else
+		reg &= ~MX51_ECSPI_TESTREG_LBC;
+	writel(reg, spi_imx->base + MX51_ECSPI_TESTREG);
+
 	writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
 	writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG);
 
@@ -1141,7 +1151,8 @@ static int spi_imx_probe(struct platform_device *pdev)
 	spi_imx->bitbang.master->cleanup = spi_imx_cleanup;
 	spi_imx->bitbang.master->prepare_message = spi_imx_prepare_message;
 	spi_imx->bitbang.master->unprepare_message = spi_imx_unprepare_message;
-	spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+	spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH |
+					     SPI_LOOP;
 
 	init_completion(&spi_imx->xfer_done);
 
-- 
1.9.1

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Re: [PATCH] spi-imx: Add loopback mode support

[Fabio Estevam]

On Thu, Dec 3, 2015 at 11:23 PM, Fabio Estevam <festevam-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> From: Fabio Estevam <fabio.estevam-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
>
> Loopback mode can be activated by setting bit LBC (LoopBack
> Control) of register ECSPI_TESTREG.
>
> Add support for it.
>
> Signed-off-by: Fabio Estevam <fabio.estevam-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> ---
>  drivers/spi/spi-imx.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
> index 0e5723a..e7e4f0c 100644
> --- a/drivers/spi/spi-imx.c
> +++ b/drivers/spi/spi-imx.c
> @@ -244,6 +244,9 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
>  #define MX51_ECSPI_STAT                0x18
>  #define MX51_ECSPI_STAT_RR             (1 <<  3)
>
> +#define MX51_ECSPI_TESTREG     0x20
> +#define MX51_ECSPI_TESTREG_LBC BIT(31)
> +
>  /* MX51 eCSPI */
>  static unsigned int mx51_ecspi_clkdiv(unsigned int fin, unsigned int fspi,
>                                       unsigned int *fres)
> @@ -313,7 +316,7 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
>  {
>         u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0, dma = 0;
>         u32 tx_wml_cfg, rx_wml_cfg, rxt_wml_cfg;
> -       u32 clk = config->speed_hz, delay;
> +       u32 clk = config->speed_hz, delay, reg;
>
>         /*
>          * The hardware seems to have a race condition when changing modes. The
> @@ -351,6 +354,13 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
>         else
>                 cfg &= ~MX51_ECSPI_CONFIG_SSBPOL(config->cs);
>
> +       reg = readl(spi_imx->base + MX51_ECSPI_TESTREG);
> +       if (config->mode & SPI_LOOP)
> +               reg |= MX51_ECSPI_TESTREG_LBC;
> +       else
> +               reg &= ~MX51_ECSPI_TESTREG_LBC;
> +       writel(reg, spi_imx->base + MX51_ECSPI_TESTREG);
> +
>         writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
>         writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG);
>
> @@ -1141,7 +1151,8 @@ static int spi_imx_probe(struct platform_device *pdev)
>         spi_imx->bitbang.master->cleanup = spi_imx_cleanup;
>         spi_imx->bitbang.master->prepare_message = spi_imx_prepare_message;
>         spi_imx->bitbang.master->unprepare_message = spi_imx_unprepare_message;
> -       spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
> +       spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH |
> +                                            SPI_LOOP;

The SPI_LOOP should not be added to all spi versions, only for the
mx51/mx53/mx6q type.

Just realized that Anton sent the loopback support as part of his
series, so please discard this one.
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Re: [PATCH] spi-imx: Add loopback mode support

[Mark Brown]

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On Sat, Dec 05, 2015 at 03:32:31PM -0200, Fabio Estevam wrote:

> The SPI_LOOP should not be added to all spi versions, only for the
> mx51/mx53/mx6q type.

> Just realized that Anton sent the loopback support as part of his
> series, so please discard this one.

I'd already applied this before you sent your mail, sorry.

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Re: [PATCH] spi-imx: Add loopback mode support

[Anton Bondarenko]

On 2015-12-06 12:24, Mark Brown wrote:
> On Sat, Dec 05, 2015 at 03:32:31PM -0200, Fabio Estevam wrote:
>
>> The SPI_LOOP should not be added to all spi versions, only for the
>> mx51/mx53/mx6q type.
>
>> Just realized that Anton sent the loopback support as part of his
>> series, so please discard this one.
>
> I'd already applied this before you sent your mail, sorry.
>

I'll rebase my changes on top of topic/imx. Is it OK?

Regards, Anton
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Re: [PATCH] spi-imx: Add loopback mode support

[Mark Brown]

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On Sun, Dec 06, 2015 at 01:49:56PM +0100, Anton Bondarenko wrote:
> On 2015-12-06 12:24, Mark Brown wrote:

> >I'd already applied this before you sent your mail, sorry.

> I'll rebase my changes on top of topic/imx. Is it OK?

Yes, totally fine - please go ahead.

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Re: [PATCH] spi-imx: Add loopback mode support

[Anton Bondarenko]

On 2015-12-07 20:16, Mark Brown wrote:
> On Sun, Dec 06, 2015 at 01:49:56PM +0100, Anton Bondarenko wrote:
>> On 2015-12-06 12:24, Mark Brown wrote:
>
>>> I'd already applied this before you sent your mail, sorry.
>
>> I'll rebase my changes on top of topic/imx. Is it OK?
>
> Yes, totally fine - please go ahead.
>

Fix for this commit provided in [PATCH v6 01/08].
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Re: [PATCH] spi-imx: Add loopback mode support

[Fabio Estevam]

On Sun, Dec 6, 2015 at 9:24 AM, Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> On Sat, Dec 05, 2015 at 03:32:31PM -0200, Fabio Estevam wrote:
>
>> The SPI_LOOP should not be added to all spi versions, only for the
>> mx51/mx53/mx6q type.
>
>> Just realized that Anton sent the loopback support as part of his
>> series, so please discard this one.
>
> I'd already applied this before you sent your mail, sorry.

No problekm, Mark. I think Anton can move the SPI_LOOP flag from the
probe function to only mx51/mx53/mx6 config and all will be fine.

Thanks
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Re: [PATCH] spi-imx: Add loopback mode support

[Anton Bondarenko]

On 2015-12-06 15:51, Fabio Estevam wrote:
> On Sun, Dec 6, 2015 at 9:24 AM, Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
>> On Sat, Dec 05, 2015 at 03:32:31PM -0200, Fabio Estevam wrote:
>>
>>> The SPI_LOOP should not be added to all spi versions, only for the
>>> mx51/mx53/mx6q type.
>>
>>> Just realized that Anton sent the loopback support as part of his
>>> series, so please discard this one.
>>
>> I'd already applied this before you sent your mail, sorry.
>
> No problekm, Mark. I think Anton can move the SPI_LOOP flag from the
> probe function to only mx51/mx53/mx6 config and all will be fine.
>
> Thanks
>

There is a small problem with this change. Loopback mode not enabled for 
first transaction in the system. This is happen because TEST reg written 
before controller taken out from the reset by writing to CTRL reg. The 
simple fix will be to move TEST reg read/write after write to CTRL reg.

Regards, Anton
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Re: [PATCH] spi-imx: Add loopback mode support

[Fabio Estevam]

Hi Anton,

On Sun, Dec 6, 2015 at 4:06 PM, Anton Bondarenko
<anton.bondarenko.sama-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

>
> There is a small problem with this change. Loopback mode not enabled for
> first transaction in the system. This is happen because TEST reg written
> before controller taken out from the reset by writing to CTRL reg. The
> simple fix will be to move TEST reg read/write after write to CTRL reg.

Could you please fix this as part of your series?

Thanks
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