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    SubjectRe: [PATCH v4 1/2] dmaengine: at_hdmac: platform data move to use .id_table
    On Mon, Oct 17, 2011 at 02:56:40PM +0200, Nicolas Ferre wrote:
    > We remove the use of platform data from DMA controller driver.
    > We now use of .id_table to distinguish between compatible
    > types. The two implementations allow to determine the
    > number of channels and the capabilities of the controller.
    >
    > Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
    > Acked-by: Grant Likely <grant.likely@secretlab.ca>
    > ---
    > drivers/dma/at_hdmac.c | 48 ++++++++++++++++++++++++++++++++++---------
    > drivers/dma/at_hdmac_regs.h | 8 +++++++
    > 2 files changed, 46 insertions(+), 10 deletions(-)
    >
    > diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
    > index fcfa0a8..d1869c5 100644
    > --- a/drivers/dma/at_hdmac.c
    > +++ b/drivers/dma/at_hdmac.c
    > @@ -1175,6 +1175,18 @@ static void atc_free_chan_resources(struct dma_chan *chan)
    >
    > /*-- Module Management -----------------------------------------------*/
    >
    > +static struct platform_device_id atdma_devtypes[] = {
    > + {
    > + .name = "at91sam9rl_dma",
    > + .driver_data = ATDMA_DEVTYPE_SAM9RL,
    > + }, {
    > + .name = "at91sam9g45_dma",
    > + .driver_data = ATDMA_DEVTYPE_SAM9G45,
    > + }, {
    > + /* sentinel */
    > + }
    > +};
    > +
    > /**
    > * at_dma_off - disable DMA controller
    > * @atdma: the Atmel HDAMC device
    > @@ -1193,18 +1205,32 @@ static void at_dma_off(struct at_dma *atdma)
    >
    > static int __init at_dma_probe(struct platform_device *pdev)
    > {
    > - struct at_dma_platform_data *pdata;
    > struct resource *io;
    > struct at_dma *atdma;
    > size_t size;
    > int irq;
    > int err;
    > int i;
    > + u32 nr_channels;
    > + dma_cap_mask_t cap_mask = {};
    > + enum atdma_devtype atdmatype;
    > +
    > + dma_cap_set(DMA_MEMCPY, cap_mask);
    > +
    > + /* get DMA parameters from controller type */
    > + atdmatype = platform_get_device_id(pdev)->driver_data;
    >
    > - /* get DMA Controller parameters from platform */
    > - pdata = pdev->dev.platform_data;
    > - if (!pdata || pdata->nr_channels > AT_DMA_MAX_NR_CHANNELS)
    > + switch (atdmatype) {
    > + case ATDMA_DEVTYPE_SAM9RL:
    > + nr_channels = 2;
    > + break;
    > + case ATDMA_DEVTYPE_SAM9G45:
    > + nr_channels = 8;
    > + dma_cap_set(DMA_SLAVE, cap_mask);
    > + break;
    > + default:
    > return -EINVAL;

    Instead of this song and dance, why not make a configuration structure
    and embed that into the platform_device_id table? Like this:

    struct at_dma_platform_data at91sam9rl_config {
    .nr_channels = 2;
    .cap_mask = 0;
    };
    struct at_dma_platform_data at91samg45_config {
    .nr_channels = 8;
    .cap_mask = DMA_SLAVE;
    };
    static struct platform_device_id atdma_devtypes[] = {
    {
    .name = "at91sam9rl_dma",
    .driver_data = (unsigned long) at91sam9rl_config,
    /*
    * Yes, I know, ugly cast; but one case will be needed
    * regardless when the of_device_id table is added.
    * It's due to the platform_device_id not using a
    * void*
    */
    }, {
    .name = "at91sam9g45_dma",
    .driver_data = (unsigned long) at91sam9g45_config,
    }, {
    /* sentinel */
    }
    };

    And then the enum can be eliminated entirely.

    > + }
    >
    > io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    > if (!io)
    > @@ -1215,14 +1241,15 @@ static int __init at_dma_probe(struct platform_device *pdev)
    > return irq;
    >
    > size = sizeof(struct at_dma);
    > - size += pdata->nr_channels * sizeof(struct at_dma_chan);
    > + size += nr_channels * sizeof(struct at_dma_chan);
    > atdma = kzalloc(size, GFP_KERNEL);
    > if (!atdma)
    > return -ENOMEM;
    >
    > - /* discover transaction capabilites from the platform data */
    > - atdma->dma_common.cap_mask = pdata->cap_mask;
    > - atdma->all_chan_mask = (1 << pdata->nr_channels) - 1;
    > + /* discover transaction capabilities */
    > + atdma->dma_common.cap_mask = cap_mask;
    > + atdma->all_chan_mask = (1 << nr_channels) - 1;
    > + atdma->devtype = atdmatype;
    >
    > size = resource_size(io);
    > if (!request_mem_region(io->start, size, pdev->dev.driver->name)) {
    > @@ -1268,7 +1295,7 @@ static int __init at_dma_probe(struct platform_device *pdev)
    >
    > /* initialize channels related values */
    > INIT_LIST_HEAD(&atdma->dma_common.channels);
    > - for (i = 0; i < pdata->nr_channels; i++) {
    > + for (i = 0; i < nr_channels; i++) {
    > struct at_dma_chan *atchan = &atdma->chan[i];
    >
    > atchan->chan_common.device = &atdma->dma_common;
    > @@ -1313,7 +1340,7 @@ static int __init at_dma_probe(struct platform_device *pdev)
    > dev_info(&pdev->dev, "Atmel AHB DMA Controller ( %s%s), %d channels\n",
    > dma_has_cap(DMA_MEMCPY, atdma->dma_common.cap_mask) ? "cpy " : "",
    > dma_has_cap(DMA_SLAVE, atdma->dma_common.cap_mask) ? "slave " : "",
    > - pdata->nr_channels);
    > + nr_channels);
    >
    > dma_async_device_register(&atdma->dma_common);
    >
    > @@ -1495,6 +1522,7 @@ static const struct dev_pm_ops at_dma_dev_pm_ops = {
    > static struct platform_driver at_dma_driver = {
    > .remove = __exit_p(at_dma_remove),
    > .shutdown = at_dma_shutdown,
    > + .id_table = atdma_devtypes,
    > .driver = {
    > .name = "at_hdmac",
    > .pm = &at_dma_dev_pm_ops,
    > diff --git a/drivers/dma/at_hdmac_regs.h b/drivers/dma/at_hdmac_regs.h
    > index aa4c9ae..d7d6737 100644
    > --- a/drivers/dma/at_hdmac_regs.h
    > +++ b/drivers/dma/at_hdmac_regs.h
    > @@ -248,9 +248,16 @@ static inline struct at_dma_chan *to_at_dma_chan(struct dma_chan *dchan)
    >
    > /*-- Controller ------------------------------------------------------*/
    >
    > +enum atdma_devtype {
    > + ATDMA_DEVTYPE_UNDEFINED = 0,
    > + ATDMA_DEVTYPE_SAM9RL, /* compatible with SAM9RL DMA controller */
    > + ATDMA_DEVTYPE_SAM9G45, /* compatible with SAM9G45 DMA controller */
    > +};
    > +
    > /**
    > * struct at_dma - internal representation of an Atmel HDMA Controller
    > * @chan_common: common dmaengine dma_device object members
    > + * @atdma_devtype: identifier of DMA controller compatibility
    > * @ch_regs: memory mapped register base
    > * @clk: dma controller clock
    > * @save_imr: interrupt mask register that is saved on suspend/resume cycle
    > @@ -260,6 +267,7 @@ static inline struct at_dma_chan *to_at_dma_chan(struct dma_chan *dchan)
    > */
    > struct at_dma {
    > struct dma_device dma_common;
    > + enum atdma_devtype devtype;
    > void __iomem *regs;
    > struct clk *clk;
    > u32 save_imr;
    > --
    > 1.7.5.4
    >


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