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Date: Thu, 15 Nov 2012 16:20:42 +0000
From: Grant Likely <grant.likely@...retlab.ca>
To: Murali Karicheri <m-karicheri2@...com>, rob.herring@...xeda.com,
rob@...dley.net, devicetree-discuss@...ts.ozlabs.org,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
spi-devel-general@...ts.sourceforge.net,
davinci-linux-open-source@...ux.davincidsp.com,
linux-keystone@...t.ti.com
Cc: Murali Karicheri <m-karicheri2@...com>
Subject: Re: [linux-keystone] [PATCH] spi: davinci: add OF support for the spi controller
On Mon, 12 Nov 2012 16:28:22 -0500, Murali Karicheri <m-karicheri2@...com> wrote:
> This adds OF support to DaVinci SPI controller to configure platform
> data through device bindings.
>
> Signed-off-by: Murali Karicheri <m-karicheri2@...com>
Hi Murali,
Comments below...
> ---
> .../devicetree/bindings/spi/spi-davinci.txt | 50 ++++++++++++
> drivers/spi/spi-davinci.c | 80 +++++++++++++++++++-
> 2 files changed, 126 insertions(+), 4 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/spi/spi-davinci.txt
>
> diff --git a/Documentation/devicetree/bindings/spi/spi-davinci.txt b/Documentation/devicetree/bindings/spi/spi-davinci.txt
> new file mode 100644
> index 0000000..0369369
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/spi-davinci.txt
> @@ -0,0 +1,50 @@
> +Davinci SPI controller device bindings
> +
> +Required properties:
> +- #address-cells: number of cells required to define a chip select
> + address on the SPI bus.
Will this *ever* be something other than '1'?
> +- #size-cells: should be zero.
> +- compatible:
> + - "ti,davinci-spi"
Please use the actual model of the chip here. Don't try to be generic
with the compatible string. A driver can bind against more than one
compatible value and new devices can claim compatiblity with old by
including the old compatible string in this list.
> +- reg: Offset and length of SPI controller register space
> +- ti,davinci-spi-version: SPI version :- "1.0" or "2.0"
Usually this is determined from the compatible value directly (which is
why compatible strings shouldn't be generic). Don't use a separate
property for it.
> +- ti,davinci-spi-num-cs: Number of chip selects
> +- ti,davinci-spi-intr-line: interrupt line used to connect the SPI
> + IP to the ARM interrupt controller withn the SoC. Possible values
> + are 0 and 1.
? Isn't that what the interrupts property is for? I don't understand why
this is needed from the description.
> +- interrupts: interrupt number offset at the irq parent
> +- clocks: spi clk phandle
> +
> +Example of a NOR flash slave device (n25q032) connected to DaVinci
> +SPI controller device over the SPI bus.
> +
> +spi:spi0@...F0000 {
spi@...F0000 (use 'spi' not 'spi0')
> + #address-cells = <1>;
> + #size-cells = <0>;
> + compatible = "ti,davinci-spi";
> + reg = <0x20BF0000 0x1000>;
> + ti,davinci-spi-version = "1.0";
> + ti,davinci-spi-num-cs = <4>;
> + ti,davinci-spi-intr-line = <0>;
> + interrupts = <338>;
> + clocks = <&clkspi>;
> +
> + flash: n25q032@0 {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + compatible = "st,m25p32";
> + spi-max-frequency = <25000000>;
> + reg = <0>;
> +
> + partition@0 {
> + label = "u-boot-spl";
> + reg = <0x0 0x80000>;
> + read-only;
> + };
> +
> + partition@1 {
> + label = "test";
> + reg = <0x80000 0x380000>;
> + };
> + };
> +};
> diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
> index 71a6423..0f50319 100644
> --- a/drivers/spi/spi-davinci.c
> +++ b/drivers/spi/spi-davinci.c
> @@ -26,6 +26,9 @@
> #include <linux/err.h>
> #include <linux/clk.h>
> #include <linux/dma-mapping.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/of_irq.h>
> #include <linux/spi/spi.h>
> #include <linux/spi/spi_bitbang.h>
> #include <linux/slab.h>
> @@ -788,6 +791,69 @@ rx_dma_failed:
> return r;
> }
>
> +#if defined(CONFIG_OF)
> +static const struct of_device_id davinci_spi_of_match[] = {
> + {
> + .compatible = "ti,davinci-spi",
> + },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, davini_spi_of_match);
> +
> +/**
> + * spi_davinci_get_pdata - Get platform_data from DTS binding
> + * @pdev: ptr to platform data
> + *
> + * Parses and populate platform_data from device tree bindings.
> + *
> + * NOTE: Not all platform_data params are supported currently.
> + */
> +static struct davinci_spi_platform_data
> + *spi_davinci_get_pdata(struct platform_device *pdev)
> +{
> + struct device_node *node = pdev->dev.of_node;
> + struct davinci_spi_platform_data *pdata;
> + unsigned int num_cs, intr_line = 0;
> + const char *version;
> +
> + if (pdev->dev.platform_data)
> + return pdev->dev.platform_data;
> +
> + if (!pdev->dev.of_node)
> + return NULL;
> +
> + pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
> + pdev->dev.platform_data = pdata;
> + if (!pdata)
> + return NULL;
Since pdata must always be present, roll it directly into struct
spi_davinci and get rid of the kzmalloc here. It is less expensive and
is simpler code.
> +
> + /* default version is 1.0 */
> + pdata->version = SPI_VERSION_1;
> + of_property_read_string(node, "ti,davinci-spi-version", &version);
> + if (!strcmp(version, "2.0"))
> + pdata->version = SPI_VERSION_2;
> +
> + /*
> + * default num_cs is 1 and all chipsel are internal to the chip
> + * indicated by chip_sel being NULL. GPIO based CS is not
> + * supported yet in DT bindings.
> + */
> + num_cs = 1;
> + of_property_read_u32(node, "ti,davinci-spi-num-cs", &num_cs);
> + pdata->num_chipselect = num_cs;
> + of_property_read_u32(node, "ti,davinci-spi-intr-line", &intr_line);
> + pdata->intr_line = intr_line;
> + return pdev->dev.platform_data;
> +}
> +#else
> +#define davinci_spi_of_match NULL
> +static struct davinci_spi_platform_data
> + *spi_davinci_get_pdata(struct platform_device *pdev)
> +{
> + return pdev->dev.platform_data;
> +}
> +#endif
> +
> /**
> * davinci_spi_probe - probe function for SPI Master Controller
> * @pdev: platform_device structure which contains plateform specific data
> @@ -801,16 +867,16 @@ rx_dma_failed:
> */
> static int __devinit davinci_spi_probe(struct platform_device *pdev)
> {
> + resource_size_t dma_rx_chan = SPI_NO_RESOURCE;
> + resource_size_t dma_tx_chan = SPI_NO_RESOURCE;
> + struct davinci_spi_platform_data *pdata;
> struct spi_master *master;
> struct davinci_spi *dspi;
> - struct davinci_spi_platform_data *pdata;
> struct resource *r, *mem;
> - resource_size_t dma_rx_chan = SPI_NO_RESOURCE;
> - resource_size_t dma_tx_chan = SPI_NO_RESOURCE;
> int i = 0, ret = 0;
> u32 spipc0;
>
> - pdata = pdev->dev.platform_data;
> + pdata = spi_davinci_get_pdata(pdev);
> if (pdata == NULL) {
> ret = -ENODEV;
> goto err;
> @@ -851,7 +917,11 @@ static int __devinit davinci_spi_probe(struct platform_device *pdev)
> goto release_region;
> }
>
> + /* first get irq through resource table, else try of irq method */
> dspi->irq = platform_get_irq(pdev, 0);
> + if (dspi->irq <= 0)
> + dspi->irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
> +
This should never be needed. The irq should already be populated in the
platform_device.
> if (dspi->irq <= 0) {
> ret = -EINVAL;
> goto unmap_io;
> @@ -875,6 +945,7 @@ static int __devinit davinci_spi_probe(struct platform_device *pdev)
> }
> clk_prepare_enable(dspi->clk);
>
> + master->dev.of_node = pdev->dev.of_node;
> master->bus_num = pdev->id;
> master->num_chipselect = pdata->num_chipselect;
> master->setup = davinci_spi_setup;
> @@ -1010,6 +1081,7 @@ static struct platform_driver davinci_spi_driver = {
> .driver = {
> .name = "spi_davinci",
> .owner = THIS_MODULE,
> + .of_match_table = davinci_spi_of_match,
> },
> .probe = davinci_spi_probe,
> .remove = __devexit_p(davinci_spi_remove),
> --
> 1.7.9.5
>
--
Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies, Ltd.
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