[RK3288][Android6.0] 除錯筆記 --- 測試I2C裝置正常傳輸方法
阿新 • • 發佈：2018-12-22
Platform: Rockchip
OS: Android 6.0
Kernel: 3.10.92
rk在驅動層做了一個通用i2c測試程式碼提供給上層快速測試i2c外設是否傳輸正常.
測試使用方法:#echo [0-5] > /dev/i2c_detect //0-5表示i2c number號,不過i2c5需要修改下驅動,預設只支援到i2c4.
例如我的i2c2接的是audio codec:
[email protected]:/ # echo 2 > /dev/i2c_detect&i2c2 { status = "okay"; rt5631: [email protected] { compatible = "rt5631"; reg = <0x1a>; }; };
kernel log出列印:
I2c2 slave list: 0x1a
而audio codec的地址就是0x1a.
驅動關鍵點說明:
kernel/drivers/i2c/buses/i2c-rockchip.c:
static ssize_t i2c_detect_write(struct file *file, const char __user *buf, size_t count, loff_t *offset) { char nr_buf[8]; int nr = 0, ret; /*只支援到i2c4, 如果要支援i2c5,那麼要改成5.*/ if (count > 4) return -EFAULT; ret = copy_from_user(nr_buf, buf, count); if (ret < 0) return -EFAULT; sscanf(nr_buf, "%d", &nr); /*這裡得改成6. */ if (nr >= 5 || nr < 0) return -EFAULT; slave_detect(nr); return count; } static void slave_detect(int nr) { int ret = 0; unsigned short addr; char val[8]; char buf[6 * 0x80 + 20]; struct i2c_client client; memset(buf, 0, 6 * 0x80 + 20); sprintf(buf, "I2c%d slave list: ", nr); do { /*掃描0x01~0x80地址範圍的裝置.*/ for (addr = 0x01; addr < 0x80; addr++) { detect_set_client(&client, addr, nr); /*讀取一個位元組.*/ ret = detect_read(&client, val, 1); if (ret > 0) sprintf(buf, "%s 0x%02x", buf, addr); } /*列印掃描到的裝置地址.*/ printk("%s\n", buf); } while (0); } static int detect_read(struct i2c_client *client, char *buf, int len) { struct i2c_msg msg; msg.addr = client->addr; msg.flags = client->flags | I2C_M_RD; msg.buf = buf; msg.len = len; /*以100kHz的速率讀取*/ #ifdef CONFIG_I2C_ROCKCHIP_COMPAT msg.scl_rate = 100 * 1000; #endif return i2c_transfer(client->adapter, &msg, 1); }