Re: [PATCH] i2c: add bcm2835 driver
From: Grant Likely <hidden>
Date: 2013-02-08 21:48:46
Also in:
linux-arm-kernel, linux-i2c
On Wed, 2 Jan 2013 22:46:18 -0700, Stephen Warren [off-list ref] wrote:
quoted hunk
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 <redacted> --- .../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.cdiff --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-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> g.