[1/2] dt-bindings: sdhci-of-at91: add the microchip,sdcal-inverted property
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Message ID 4d269f30b1122487a2b5c8b48e24f78f2b75a509.1570537903.git.nicolas.ferre@microchip.com
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  • [1/2] dt-bindings: sdhci-of-at91: add the microchip,sdcal-inverted property
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Commit Message

Nicolas Ferre Oct. 8, 2019, 12:34 p.m. UTC
Add the specific microchip,sdcal-inverted property to at91 sdhci
device binding.
This optional property describes how the SoC SDCAL pin is connected.
It could be handled at SiP, SoM or board level.

This property read by at91 sdhci driver will allow to put in place a
software workaround that would reduce power consumption.

Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
---
 Documentation/devicetree/bindings/mmc/sdhci-atmel.txt | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Ludovic Desroches Oct. 11, 2019, 12:41 p.m. UTC | #1
On Tue, Oct 08, 2019 at 02:34:32PM +0200, Nicolas Ferre wrote:
> Add a property to keep the analog calibration cell powered.
> This feature is specific to the Microchip SDHCI IP and outside
> of the standard SDHCI register map.
> 
> By always keeping it on, after a full reset sequence, we make sure
> that this feature is activated and not disabled.
> 
> We expose a hardware property to the DT as this feature can be used
> to adapt SDHCI behavior vs. how the SDCAL SoC pin is connected
> on the board.
> 
> Note that managing properly this property would reduce
> power consumption on some SAMA5D2 SiP revisions.
> 
> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>

Thanks

Ludovic

> ---
>  drivers/mmc/host/sdhci-of-at91.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
> index e7d1920729fb..9571c4a882a9 100644
> --- a/drivers/mmc/host/sdhci-of-at91.c
> +++ b/drivers/mmc/host/sdhci-of-at91.c
> @@ -27,6 +27,9 @@
>  #define SDMMC_CACR	0x230
>  #define		SDMMC_CACR_CAPWREN	BIT(0)
>  #define		SDMMC_CACR_KEY		(0x46 << 8)
> +#define SDMMC_CALCR	0x240
> +#define		SDMMC_CALCR_EN		BIT(0)
> +#define		SDMMC_CALCR_ALWYSON	BIT(4)
>  
>  #define SDHCI_AT91_PRESET_COMMON_CONF	0x400 /* drv type B, programmable clock mode */
>  
> @@ -35,6 +38,7 @@ struct sdhci_at91_priv {
>  	struct clk *gck;
>  	struct clk *mainck;
>  	bool restore_needed;
> +	bool cal_always_on;
>  };
>  
>  static void sdhci_at91_set_force_card_detect(struct sdhci_host *host)
> @@ -116,10 +120,17 @@ static void sdhci_at91_set_uhs_signaling(struct sdhci_host *host,
>  
>  static void sdhci_at91_reset(struct sdhci_host *host, u8 mask)
>  {
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
> +
>  	sdhci_reset(host, mask);
>  
>  	if (host->mmc->caps & MMC_CAP_NONREMOVABLE)
>  		sdhci_at91_set_force_card_detect(host);
> +
> +	if (priv->cal_always_on && (mask & SDHCI_RESET_ALL))
> +		sdhci_writel(host, SDMMC_CALCR_ALWYSON | SDMMC_CALCR_EN,
> +			     SDMMC_CALCR);
>  }
>  
>  static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
> @@ -345,6 +356,14 @@ static int sdhci_at91_probe(struct platform_device *pdev)
>  
>  	priv->restore_needed = false;
>  
> +	/*
> +	 * if SDCAL pin is wrongly connected, we must enable
> +	 * the analog calibration cell permanently.
> +	 */
> +	priv->cal_always_on =
> +		device_property_read_bool(&pdev->dev,
> +					  "microchip,sdcal-inverted");
> +
>  	ret = mmc_of_parse(host->mmc);
>  	if (ret)
>  		goto clocks_disable_unprepare;
> -- 
> 2.17.1
>
Rob Herring Oct. 15, 2019, 10:25 p.m. UTC | #2
On Tue, 8 Oct 2019 14:34:31 +0200, Nicolas Ferre wrote:
> Add the specific microchip,sdcal-inverted property to at91 sdhci
> device binding.
> This optional property describes how the SoC SDCAL pin is connected.
> It could be handled at SiP, SoM or board level.
> 
> This property read by at91 sdhci driver will allow to put in place a
> software workaround that would reduce power consumption.
> 
> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
> ---
>  Documentation/devicetree/bindings/mmc/sdhci-atmel.txt | 5 +++++
>  1 file changed, 5 insertions(+)
> 

Reviewed-by: Rob Herring <robh@kernel.org>
Ulf Hansson Oct. 18, 2019, 10:58 a.m. UTC | #3
On Tue, 8 Oct 2019 at 14:34, Nicolas Ferre <nicolas.ferre@microchip.com> wrote:
>
> Add the specific microchip,sdcal-inverted property to at91 sdhci
> device binding.
> This optional property describes how the SoC SDCAL pin is connected.
> It could be handled at SiP, SoM or board level.
>
> This property read by at91 sdhci driver will allow to put in place a
> software workaround that would reduce power consumption.
>
> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  Documentation/devicetree/bindings/mmc/sdhci-atmel.txt | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt b/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
> index 1b662d7171a0..503c6dbac1b2 100644
> --- a/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
> +++ b/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
> @@ -9,6 +9,11 @@ Required properties:
>  - clocks:              Phandlers to the clocks.
>  - clock-names:         Must be "hclock", "multclk", "baseclk";
>
> +Optional properties:
> +- microchip,sdcal-inverted: when present, polarity on the SDCAL SoC pin is
> +  inverted. The default polarity for this signal is described in the datasheet.
> +  For instance on SAMA5D2, the pin is usually tied to the GND with a resistor
> +  and a capacitor (see "SDMMC I/O Calibration" chapter).
>
>  Example:
>
> --
> 2.17.1
>
Ulf Hansson Oct. 18, 2019, 10:58 a.m. UTC | #4
On Tue, 8 Oct 2019 at 14:34, Nicolas Ferre <nicolas.ferre@microchip.com> wrote:
>
> Add a property to keep the analog calibration cell powered.
> This feature is specific to the Microchip SDHCI IP and outside
> of the standard SDHCI register map.
>
> By always keeping it on, after a full reset sequence, we make sure
> that this feature is activated and not disabled.
>
> We expose a hardware property to the DT as this feature can be used
> to adapt SDHCI behavior vs. how the SDCAL SoC pin is connected
> on the board.
>
> Note that managing properly this property would reduce
> power consumption on some SAMA5D2 SiP revisions.
>
> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/host/sdhci-of-at91.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
> index e7d1920729fb..9571c4a882a9 100644
> --- a/drivers/mmc/host/sdhci-of-at91.c
> +++ b/drivers/mmc/host/sdhci-of-at91.c
> @@ -27,6 +27,9 @@
>  #define SDMMC_CACR     0x230
>  #define                SDMMC_CACR_CAPWREN      BIT(0)
>  #define                SDMMC_CACR_KEY          (0x46 << 8)
> +#define SDMMC_CALCR    0x240
> +#define                SDMMC_CALCR_EN          BIT(0)
> +#define                SDMMC_CALCR_ALWYSON     BIT(4)
>
>  #define SDHCI_AT91_PRESET_COMMON_CONF  0x400 /* drv type B, programmable clock mode */
>
> @@ -35,6 +38,7 @@ struct sdhci_at91_priv {
>         struct clk *gck;
>         struct clk *mainck;
>         bool restore_needed;
> +       bool cal_always_on;
>  };
>
>  static void sdhci_at91_set_force_card_detect(struct sdhci_host *host)
> @@ -116,10 +120,17 @@ static void sdhci_at91_set_uhs_signaling(struct sdhci_host *host,
>
>  static void sdhci_at91_reset(struct sdhci_host *host, u8 mask)
>  {
> +       struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +       struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
> +
>         sdhci_reset(host, mask);
>
>         if (host->mmc->caps & MMC_CAP_NONREMOVABLE)
>                 sdhci_at91_set_force_card_detect(host);
> +
> +       if (priv->cal_always_on && (mask & SDHCI_RESET_ALL))
> +               sdhci_writel(host, SDMMC_CALCR_ALWYSON | SDMMC_CALCR_EN,
> +                            SDMMC_CALCR);
>  }
>
>  static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
> @@ -345,6 +356,14 @@ static int sdhci_at91_probe(struct platform_device *pdev)
>
>         priv->restore_needed = false;
>
> +       /*
> +        * if SDCAL pin is wrongly connected, we must enable
> +        * the analog calibration cell permanently.
> +        */
> +       priv->cal_always_on =
> +               device_property_read_bool(&pdev->dev,
> +                                         "microchip,sdcal-inverted");
> +
>         ret = mmc_of_parse(host->mmc);
>         if (ret)
>                 goto clocks_disable_unprepare;
> --
> 2.17.1
>

Patch
diff mbox series

diff --git a/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt b/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
index 1b662d7171a0..503c6dbac1b2 100644
--- a/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
+++ b/Documentation/devicetree/bindings/mmc/sdhci-atmel.txt
@@ -9,6 +9,11 @@  Required properties:
 - clocks:		Phandlers to the clocks.
 - clock-names:		Must be "hclock", "multclk", "baseclk";
 
+Optional properties:
+- microchip,sdcal-inverted: when present, polarity on the SDCAL SoC pin is
+  inverted. The default polarity for this signal is described in the datasheet.
+  For instance on SAMA5D2, the pin is usually tied to the GND with a resistor
+  and a capacitor (see "SDMMC I/O Calibration" chapter).
 
 Example: