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Date:	Mon, 28 Jul 2014 14:21:03 +0200
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Jiri Prchal <jiri.prchal@...ignal.cz>
Cc:	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, nicolas.ferre@...el.com,
	voice.shen@...el.com
Subject: Re: [PATCH] ARM: at91: spi: request all csgpio in spi probe

Hi,

Thank you for that patch, a few questions/comments below.

On 28/07/2014 at 13:43:40 +0200, Jiri Prchal wrote :
> This fix problem with PA14 set as periph A left from ROMBOOT and need it
> to be set to gpio before spi bus communicate with chip on CS0 on other
> gpio. As I reported a week ago.
> Request all csgpios in spi_probe since cs depends on each other and must
> be all of them in right state before any communication on bus. They are
> part of bus, like miso, mosi, clk, not part of chips, they are defined
> in parent spi node, not in child chip node.
> Csgpio moved to atmel_spi struct as part of master bus.
> 
> Signed-off-by: Jiri Prchal <jiri.prchal@...ignal.cz>
> ---
>  drivers/spi/spi-atmel.c | 68 +++++++++++++++++++++++++++++--------------------
>  1 file changed, 41 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
> index 92a6f0d..1fb7bb9 100644
> --- a/drivers/spi/spi-atmel.c
> +++ b/drivers/spi/spi-atmel.c
> @@ -22,11 +22,14 @@
>  #include <linux/platform_data/atmel.h>
>  #include <linux/platform_data/dma-atmel.h>
>  #include <linux/of.h>
> +#include <linux/of_gpio.h>
>  
>  #include <linux/io.h>
>  #include <linux/gpio.h>
>  #include <linux/pinctrl/consumer.h>
>  
> +#define DRIVER_NAME "atmel-spi"
> +

This is not really related to the issue solved by that patch, maybe it
could go in another patch ?

>  /* SPI register offsets */
>  #define SPI_CR					0x0000
>  #define SPI_MR					0x0004
> @@ -242,11 +245,13 @@ struct atmel_spi {
>  
>  	bool			keep_cs;
>  	bool			cs_active;
> +
> +	/* chip selects */
> +	unsigned int		csgpio[];
>  };
>  
>  /* Controller-specific per-slave state */
>  struct atmel_spi_device {
> -	unsigned int		npcs_pin;
>  	u32			csr;
>  };
>  
> @@ -312,7 +317,7 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
>  		}
>  
>  		mr = spi_readl(as, MR);
> -		gpio_set_value(asd->npcs_pin, active);
> +		gpio_set_value(as->csgpio[spi->chip_select], active);
>  	} else {
>  		u32 cpol = (spi->mode & SPI_CPOL) ? SPI_BIT(CPOL) : 0;
>  		int i;
> @@ -329,18 +334,16 @@ static void cs_activate(struct atmel_spi *as, struct spi_device *spi)
>  		mr = spi_readl(as, MR);
>  		mr = SPI_BFINS(PCS, ~(1 << spi->chip_select), mr);
>  		if (spi->chip_select != 0)
> -			gpio_set_value(asd->npcs_pin, active);
> +			gpio_set_value(as->csgpio[spi->chip_select], active);
>  		spi_writel(as, MR, mr);
>  	}
>  
>  	dev_dbg(&spi->dev, "activate %u%s, mr %08x\n",
> -			asd->npcs_pin, active ? " (high)" : "",
> -			mr);
> +		as->csgpio[spi->chip_select], active ? " (high)" : "", mr);
>  }
>  
>  static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi)
>  {
> -	struct atmel_spi_device *asd = spi->controller_state;
>  	unsigned active = spi->mode & SPI_CS_HIGH;
>  	u32 mr;
>  
> @@ -354,11 +357,10 @@ static void cs_deactivate(struct atmel_spi *as, struct spi_device *spi)
>  	}
>  
>  	dev_dbg(&spi->dev, "DEactivate %u%s, mr %08x\n",
> -			asd->npcs_pin, active ? " (low)" : "",
> -			mr);
> +		as->csgpio[spi->chip_select], active ? " (low)" : "", mr);
>  
>  	if (atmel_spi_is_v2(as) || spi->chip_select != 0)
> -		gpio_set_value(asd->npcs_pin, !active);
> +		gpio_set_value(as->csgpio[spi->chip_select], !active);
>  }
>  
>  static void atmel_spi_lock(struct atmel_spi *as) __acquires(&as->lock)
> @@ -989,8 +991,6 @@ static int atmel_spi_setup(struct spi_device *spi)
>  	struct atmel_spi_device	*asd;
>  	u32			csr;
>  	unsigned int		bits = spi->bits_per_word;
> -	unsigned int		npcs_pin;
> -	int			ret;
>  
>  	as = spi_master_get_devdata(spi->master);
>  
> @@ -1017,27 +1017,13 @@ static int atmel_spi_setup(struct spi_device *spi)
>  	csr |= SPI_BF(DLYBS, 0);
>  	csr |= SPI_BF(DLYBCT, 0);
>  
> -	/* chipselect must have been muxed as GPIO (e.g. in board setup) */
> -	npcs_pin = (unsigned int)spi->controller_data;
> -
> -	if (gpio_is_valid(spi->cs_gpio))
> -		npcs_pin = spi->cs_gpio;
> -
>  	asd = spi->controller_state;
>  	if (!asd) {
>  		asd = kzalloc(sizeof(struct atmel_spi_device), GFP_KERNEL);
>  		if (!asd)
>  			return -ENOMEM;
>  
> -		ret = gpio_request(npcs_pin, dev_name(&spi->dev));
> -		if (ret) {
> -			kfree(asd);
> -			return ret;
> -		}
> -
> -		asd->npcs_pin = npcs_pin;
>  		spi->controller_state = asd;
> -		gpio_direction_output(npcs_pin, !(spi->mode & SPI_CS_HIGH));
>  	}
>  
>  	asd->csr = csr;
> @@ -1290,6 +1276,15 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  	int			ret;
>  	struct spi_master	*master;
>  	struct atmel_spi	*as;
> +	struct device_node *np = pdev->dev.of_node;
> +	int num_cs, i;
> +
> +	if (!np)
> +		return -EINVAL;
> +
> +	num_cs = of_gpio_named_count(np, "cs-gpios");
> +	if (num_cs < 0)
> +		return num_cs;
>  

This driver can still be probed without DT, this will break here, please
don't assume that DT is present.


>  	/* Select default pin state */
>  	pinctrl_pm_select_default_state(&pdev->dev);
> @@ -1308,7 +1303,7 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  
>  	/* setup spi core then atmel-specific driver state */
>  	ret = -ENOMEM;
> -	master = spi_alloc_master(&pdev->dev, sizeof(*as));
> +	master = spi_alloc_master(&pdev->dev, sizeof(*as) + num_cs * sizeof(unsigned));
>  	if (!master)
>  		goto out_free;
>  
> @@ -1317,7 +1312,7 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(8, 16);
>  	master->dev.of_node = pdev->dev.of_node;
>  	master->bus_num = pdev->id;
> -	master->num_chipselect = master->dev.of_node ? 0 : 4;
> +	master->num_chipselect = num_cs;

My guess is that you don't need to change that part.

>  	master->setup = atmel_spi_setup;
>  	master->transfer_one_message = atmel_spi_transfer_one_message;
>  	master->cleanup = atmel_spi_cleanup;
> @@ -1325,6 +1320,25 @@ static int atmel_spi_probe(struct platform_device *pdev)
>  
>  	as = spi_master_get_devdata(master);
>  
> +	for (i = 0; i < master->num_chipselect; ++i) {
> +		ret = of_get_named_gpio(np, "cs-gpios", i);

Again, DT maybe not be compiled in or that driver may be probed from
platform data.

> +		if (ret < 0) {
> +			dev_err(&pdev->dev, "failed to get csgpio#%u (%d)\n",
> +				i, ret);
> +			goto out_free;
> +		}
> +		as->csgpio[i] = ret;
> +		dev_dbg(&pdev->dev, "csgpio#%u = %u\n", i, as->csgpio[i]);
> +		ret = devm_gpio_request_one(&pdev->dev, as->csgpio[i],
> +					    GPIOF_OUT_INIT_HIGH, DRIVER_NAME);
> +		if (ret < 0) {
> +			dev_err(&pdev->dev,
> +				"failed to configure csgpio#%u (%d)\n",
> +				i, ret);
> +			goto out_free;
> +		}
> +	}
> +
>  	/*
>  	 * Scratch buffer is used for throwaway rx and tx data.
>  	 * It's coherent to minimize dcache pollution.
> -- 
> 1.9.1
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
--
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