[RFC PATCH] spi: add at25 spi eeprom driver

[Sascha Hauer]

Hi Hubert,

On Thu, Jun 16, 2011 at 10:12:43AM +0200, Hubert Feurstein wrote:
>  obj-y	+= mfd/
>  obj-$(CONFIG_LED) += led/
> +obj-y	+= misc/
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig

I think we should move the driver up to drivers/eeprom and skip the
'misc'. The kernel guys like to get rid of it also.

> +
> +		/* Wait for non-busy status */
> +		start_time = get_time_ns();
> +
> +		retries = 0;
> +		do {
> +
> +			sr = spi_w8r8(at25->spi, AT25_RDSR);
> +			if (sr < 0 || (sr & AT25_SR_nRDY)) {
> +				dev_dbg(at25->cdev.dev,
> +					"rdsr --> %d (%02x)\n", sr, sr);
> +				mdelay(1);
> +				continue;
> +			}
> +			if (!(sr & AT25_SR_nRDY))
> +				break;
> +		} while (retries++ < 3 || !is_timeout(start_time, EE_TIMEOUT));

I don't understand this. The loop is limited by retries++ < 3. Why this
additional is_timeout? Is this the same in the kernel?

> +static int at25_init(void)
> +{
> +	register_driver(&at25_driver);
> +	return 0;
> +}
> +
> +device_initcall(at25_init);
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index 4560259..6456897 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -75,6 +75,7 @@ struct spi_device *spi_new_device(struct spi_master *master,
>  	proxy->chip_select = chip->chip_select;
>  	proxy->max_speed_hz = chip->max_speed_hz;
>  	proxy->mode = chip->mode;
> +	proxy->dev.platform_data = chip->platform_data;

This should be a seperate patch.

>  	strcpy(proxy->dev.name, chip->name);
>  	proxy->dev.type_data = proxy;
>  	status = register_device(&proxy->dev);
> @@ -194,3 +195,44 @@ int spi_sync(struct spi_device *spi, struct spi_message *message)
>  	return spi->master->transfer(spi, message);
>  }
> 
> +/**
> + * spi_write_then_read - SPI synchronous write followed by read
> + * @spi: device with which data will be exchanged
> + * @txbuf: data to be written
> + * @n_tx: size of txbuf, in bytes
> + * @rxbuf: buffer into which data will be read
> + * @n_rx: size of rxbuf, in bytes
> + * Context: can sleep
> + *
> + * This performs a half duplex MicroWire style transaction with the
> + * device, sending txbuf and then reading rxbuf.  The return value
> + * is zero for success, else a negative errno status code.
> + * This call may only be used from a context that may sleep.
> + */
> +int spi_write_then_read(struct spi_device *spi,
> +		const void *txbuf, unsigned n_tx,
> +		void *rxbuf, unsigned n_rx)
> +{
> +	int			status;
> +	struct spi_message	message;
> +	struct spi_transfer	x[2];
> +
> +	spi_message_init(&message);
> +	memset(x, 0, sizeof x);
> +	if (n_tx) {
> +		x[0].len = n_tx;
> +		spi_message_add_tail(&x[0], &message);
> +	}
> +	if (n_rx) {
> +		x[1].len = n_rx;
> +		spi_message_add_tail(&x[1], &message);
> +	}
> +
> +	x[0].tx_buf = txbuf;
> +	x[1].rx_buf = rxbuf;
> +
> +	/* do the i/o */
> +	status = spi_sync(spi, &message);
> +	return status;
> +}
> +EXPORT_SYMBOL(spi_write_then_read);

Also a seperate patch.

Sascha

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