On Wed, Feb 17, 2010 at 11:19 AM, Ernst Schwab <esch...@online.de> wrote:
> From: Ernst Schwab <esch...@online.de>
>
> Modification of the mmc_spi driver to use the SPI bus locking API.
> With this, the mmc_spi driver can be used together with other SPI
> devices on the same SPI bus. The exclusive access to the SPI bus is
> now managed in the SPI layer. The counting of chip selects in the probe
> function is no longer needed.
>
> Signed-off-by: Ernst Schwab <esch...@online.de>
Looks good to me.
g.
> ---
> diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c
> --- a/drivers/mmc/host/mmc_spi.c
> +++ b/drivers/mmc/host/mmc_spi.c
> @@ -181,7 +181,7 @@ mmc_spi_readbytes(struct mmc_spi_host *host, unsigned len)
> host->data_dma, sizeof(*host->data),
> DMA_FROM_DEVICE);
>
> - status = spi_sync(host->spi, &host->readback);
> + status = spi_sync_locked(host->spi, &host->readback);
>
> if (host->dma_dev)
> dma_sync_single_for_cpu(host->dma_dev,
> @@ -540,7 +540,7 @@ mmc_spi_command_send(struct mmc_spi_host *host,
> host->data_dma, sizeof(*host->data),
> DMA_BIDIRECTIONAL);
> }
> - status = spi_sync(host->spi, &host->m);
> + status = spi_sync_locked(host->spi, &host->m);
>
> if (host->dma_dev)
> dma_sync_single_for_cpu(host->dma_dev,
> @@ -684,7 +684,7 @@ mmc_spi_writeblock(struct mmc_spi_host *host, struct
> spi_transfer *t,
> host->data_dma, sizeof(*scratch),
> DMA_BIDIRECTIONAL);
>
> - status = spi_sync(spi, &host->m);
> + status = spi_sync_locked(spi, &host->m);
>
> if (status != 0) {
> dev_dbg(&spi->dev, "write error (%d)\n", status);
> @@ -821,7 +821,7 @@ mmc_spi_readblock(struct mmc_spi_host *host, struct
> spi_transfer *t,
> DMA_FROM_DEVICE);
> }
>
> - status = spi_sync(spi, &host->m);
> + status = spi_sync_locked(spi, &host->m);
>
> if (host->dma_dev) {
> dma_sync_single_for_cpu(host->dma_dev,
> @@ -1017,7 +1017,7 @@ mmc_spi_data_do(struct mmc_spi_host *host, struct
> mmc_command *cmd,
> host->data_dma, sizeof(*scratch),
> DMA_BIDIRECTIONAL);
>
> - tmp = spi_sync(spi, &host->m);
> + tmp = spi_sync_locked(spi, &host->m);
>
> if (host->dma_dev)
> dma_sync_single_for_cpu(host->dma_dev,
> @@ -1083,6 +1083,9 @@ static void mmc_spi_request(struct mmc_host *mmc,
> struct mmc_request *mrq)
> }
> #endif
>
> + /* request exclusive bus access */
> + spi_bus_lock(host->spi);
> +
> /* issue command; then optionally data and stop */
> status = mmc_spi_command_send(host, mrq, mrq->cmd, mrq->data != NULL);
> if (status == 0 && mrq->data) {
> @@ -1093,6 +1096,9 @@ static void mmc_spi_request(struct mmc_host *mmc,
> struct mmc_request *mrq)
> mmc_cs_off(host);
> }
>
> + /* release the bus */
> + spi_bus_unlock(host->spi);
> +
> mmc_request_done(host->mmc, mrq);
> }
>
> @@ -1289,23 +1295,6 @@ mmc_spi_detect_irq(int irq, void *mmc)
> return IRQ_HANDLED;
> }
>
> -struct count_children {
> - unsigned n;
> - struct bus_type *bus;
> -};
> -
> -static int maybe_count_child(struct device *dev, void *c)
> -{
> - struct count_children *ccp = c;
> -
> - if (dev->bus == ccp->bus) {
> - if (ccp->n)
> - return -EBUSY;
> - ccp->n++;
> - }
> - return 0;
> -}
> -
> static int mmc_spi_probe(struct spi_device *spi)
> {
> void *ones;
> @@ -1337,32 +1326,6 @@ static int mmc_spi_probe(struct spi_device *spi)
> return status;
> }
>
> - /* We can use the bus safely iff nobody else will interfere with us.
> - * Most commands consist of one SPI message to issue a command, then
> - * several more to collect its response, then possibly more for data
> - * transfer. Clocking access to other devices during that period will
> - * corrupt the command execution.
> - *
> - * Until we have software primitives which guarantee non-interference,
> - * we'll aim for a hardware-level guarantee.
> - *
> - * REVISIT we can't guarantee another device won't be added later...
> - */
> - if (spi->master->num_chipselect > 1) {
> - struct count_children cc;
> -
> - cc.n = 0;
> - cc.bus = spi->dev.bus;
> - status = device_for_each_child(spi->dev.parent, &cc,
> - maybe_count_child);
> - if (status < 0) {
> - dev_err(&spi->dev, "can't share SPI bus\n");
> - return status;
> - }
> -
> - dev_warn(&spi->dev, "ASSUMING SPI bus stays unshared!\n");
> - }
> -
> /* We need a supply of ones to transmit. This is the only time
> * the CPU touches these, so cache coherency isn't a concern.
> *
>
>
>
--
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
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