增加 SPI 设备驱动示例.

Signed-off-by: rick.chan <chenyang@autoai.com>

Linux/KernelDriver/4.14/SPI/Makefile

@@ -0,0 +1,14 @@
+obj-m:= \
+    demospi.o
+
+demoplatform-objs:= \
+	demo_spi.o
+
+EXTRA_CFLAGS += \
+    -I$(PWD)
+
+all:
+	$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
+
+clean:
+	$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

Linux/KernelDriver/4.14/SPI/demo_spi.c

@@ -0,0 +1,68 @@
+#include <linux/spi/spi.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+struct demo_spi_private {
+	struct regmap *regmap;
+};
+
+static const struct regmap_config demo_regmap = {
+    .reg_bits = 8,
+    .val_bits = 8,
+};
+
+static int demo_spi_probe(struct spi_device *spi)
+{
+    struct demo_spi_private *demo_spi;
+    int ret;
+
+    demo_spi = devm_kzalloc(&spi->dev, sizeof(struct demo_spi_private),
+			      GFP_KERNEL);
+	if (demo_spi == NULL)
+		return -ENOMEM;
+
+    spi->bits_per_word = 8;
+    spi->mode = SPI_MODE_0;
+    spi->max_speed_hz = 1000000;
+
+    demo_spi->regmap = devm_regmap_init_spi(spi, &demo_regmap);
+    if (IS_ERR(demo_spi->regmap))
+		return PTR_ERR(demo_spi->regmap);
+
+    spi_set_drvdata(spi, demo_spi);
+    return 0;
+}
+
+static int demo_spi_remove(struct spi_device *spi)
+{
+	return 0;
+}
+
+static const struct of_device_id demo_of_match[] = {
+	{ .compatible = "spi,demo", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, demo_of_match);
+
+static const struct spi_device_id demo_id_table[] = {
+	{ "spidemo", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, demo_id_table);
+
+static struct spi_driver demo_spi_driver = {
+	.driver  = {
+		.name   = "demo_spi",
+		.of_match_table = demo_of_match,
+	},
+	.id_table = demo_id_table,
+	.probe  = demo_spi_probe,
+	.remove = demo_spi_remove,
+};
+
+module_spi_driver(demo_spi_driver);
+
+MODULE_AUTHOR("Rick Chan <cy187lion@sina.com>");
+MODULE_DESCRIPTION("SPI driver demo");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.0.0");