On Wed, 2 Jan 2013 22:46:18 -0700, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote:
> This implements a very basic I2C host driver for the BCM2835 SoC. Missing
> features so far are:
>
> * Clock rate adjustment.
> * 10-bit addressing.
> * DMA.
>
> Signed-off-by: Stephen Warren <swarren@xxxxxxxxxxxxx>
> ---
> .../devicetree/bindings/i2c/brcm,bcm2835-i2c.txt | 20 ++
> drivers/i2c/busses/Kconfig | 12 +
> drivers/i2c/busses/Makefile | 1 +
> drivers/i2c/busses/i2c-bcm2835.c | 331 ++++++++++++++++++++
> 4 files changed, 364 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/i2c/brcm,bcm2835-i2c.txt
> create mode 100644 drivers/i2c/busses/i2c-bcm2835.c
>
> diff --git a/Documentation/devicetree/bindings/i2c/brcm,bcm2835-i2c.txt b/Documentation/devicetree/bindings/i2c/brcm,bcm2835-i2c.txt
> new file mode 100644
> index 0000000..e9de375
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/brcm,bcm2835-i2c.txt
> @@ -0,0 +1,20 @@
> +Broadcom BCM2835 I2C controller
> +
> +Required properties:
> +- compatible : Should be "brcm,bcm2835-i2c".
> +- reg: Should contain register location and length.
> +- interrupts: Should contain interrupt.
> +- clocks : The clock feeding the I2C controller.
> +
> +Recommended properties:
> +- clock-frequency : desired I2C bus clock frequency in Hz.
> +
> +Example:
> +
> +i2c@20205000 {
> + compatible = "brcm,bcm2835-i2c";
> + reg = <0x7e205000 0x1000>;
> + interrupts = <2 21>;
> + clocks = <&clk_i2c>;
> + clock-frequency = <100000>;
> +};
Looks good.
> +static int __devinit bcm2835_i2c_probe(struct platform_device *pdev)
> +{
> + struct bcm2835_i2c_dev *i2c_dev;
> + struct resource *mem, *requested, *irq;
> + int ret;
> + struct i2c_adapter *adap;
> +
> + i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
> + if (!i2c_dev) {
> + dev_err(&pdev->dev, "Cannot allocate i2c_dev\n");
> + return -ENOMEM;
> + }
> + platform_set_drvdata(pdev, i2c_dev);
> + i2c_dev->dev = &pdev->dev;
> + init_completion(&i2c_dev->completion);
> +
> + mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!mem) {
> + dev_err(&pdev->dev, "No mem resource\n");
> + return -ENODEV;
> + }
> +
> + requested = devm_request_mem_region(&pdev->dev, mem->start,
> + resource_size(mem),
> + dev_name(&pdev->dev));
> + if (!requested) {
> + dev_err(&pdev->dev, "Could not claim register region\n");
> + return -EBUSY;
> + }
> +
> + i2c_dev->regs = devm_ioremap(&pdev->dev, mem->start,
> + resource_size(mem));
> + if (!i2c_dev->regs) {
> + dev_err(&pdev->dev, "Could not map registers\n");
> + return -ENOMEM;
> + }
> +
> + irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> + if (!irq) {
> + dev_err(&pdev->dev, "No IRQ resource\n");
> + return -ENODEV;
> + }
> +
> + ret = devm_request_irq(&pdev->dev, irq->start, bcm2835_i2c_isr,
> + IRQF_SHARED, dev_name(&pdev->dev), i2c_dev);
> + if (ret) {
> + dev_err(&pdev->dev, "Could not request IRQ\n");
> + return -ENODEV;
> + }
> +
> + adap = &i2c_dev->adapter;
> + i2c_set_adapdata(adap, i2c_dev);
> + adap->owner = THIS_MODULE;
> + adap->class = I2C_CLASS_HWMON;
> + strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name));
> + adap->algo = &bcm2835_i2c_algo;
> + adap->dev.parent = &pdev->dev;
> + adap->nr = -1;
> +
> + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
> +
> + ret = i2c_add_numbered_adapter(adap);
> + if (ret) {
> + dev_err(&pdev->dev, "Could not add adapter\n");
> + return ret;
> + }
> +
> + return 0;
The driver core will print a message if things fail here. The above 6
lines can be replaced with simply:
return i2c_add_numbered_adapter(adap);
> +}
> +
> +static int bcm2835_i2c_remove(struct platform_device *pdev)
> +{
> + struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
> +
> + i2c_del_adapter(&i2c_dev->adapter);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id bcm2835_i2c_of_match[] = {
> + { .compatible = "brcm,bcm2835-i2c" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match);
> +
> +static struct platform_driver bcm2835_i2c_driver = {
> + .probe = bcm2835_i2c_probe,
> + .remove = bcm2835_i2c_remove,
> + .driver = {
> + .name = "i2c-bcm2835",
> + .owner = THIS_MODULE,
> + .of_match_table = bcm2835_i2c_of_match,
> + },
> +};
> +
> +static int __init bcm2835_i2c_init_driver(void)
> +{
> + return platform_driver_register(&bcm2835_i2c_driver);
> +}
> +module_init(bcm2835_i2c_init_driver);
> +
> +static void __exit bcm2835_i2c_exit_driver(void)
> +{
> + platform_driver_unregister(&bcm2835_i2c_driver);
> +}
> +module_exit(bcm2835_i2c_exit_driver);
Nit: module_platform_driver()
Otherwise looks pretty tight.
Reviewed-by: Grant Likely <grant.likely@xxxxxxxxxxxx>
g.
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