綦江网站建设公司,临沂建设网站公司,质感网站系统下载 锐狐,企业级软件作者信息 作者: 彭东林 邮箱#xff1a;pengdonglin137163.com QQ#xff1a;405728433 平台简介 开发板#xff1a;tiny4412ADK S700 4GB Flash 要移植的内核版本#xff1a;Linux-4.4.0 #xff08;支持device tree#xff09; u-boot版本#xff1a;友善之臂自带的… 作者信息 作者: 彭东林 邮箱pengdonglin137163.com QQ405728433 平台简介 开发板tiny4412ADK S700 4GB Flash 要移植的内核版本Linux-4.4.0 支持device tree u-boot版本友善之臂自带的 U-Boot 2010.12 为支持uImage启动做了少许改动 busybox版本busybox 1.25 交叉编译工具链 arm-none-linux-gnueabi-gcc gcc version 4.8.3 20140320 (prerelease) (Sourcery CodeBench Lite 2014.05-29) 摘要 MMA7660是一个三轴加速度传感器跟exynos4412之间使用I2C接口进行通信同时MMA7660可以向exynos4412发起外部中断。 移植MMA7660驱动会涉及到device tree、I2C驱动、中断、输入子系统等几个部分tiny4412自带的MMA7660驱动程序是不支持设备树的同时I2C驱动也没有采用设备树所以主要的工作量就是将MMA7660和I2C驱动程序从非设备树形式转变为设备树的形式。同时借此机会学习一下有设备树的情况下的设备驱动MMA7660和I2C和中断。 移植 一、原理图 下面是MMA7660的在底板原理图 可以看到使用的是第3个I2C控制器。 下面是核心板 I2C XEINT25 二、tiny4412自带的驱动 tiny4412自带的mma7660驱动并不是采用设备树但是可以作为我们的参考在arch/arm/mach-exynos/mach-tiny4412.c中包含了mma7660的板级信息。 MMA7660的板级信息 1: #include linux/mma7660.h 2: static struct mma7660_platform_data mma7660_pdata { 3: .irq IRQ_EINT(25), 4: .poll_interval 100, 5: .input_fuzz 4, 6: .input_flat 4, 7: }; 8: 9: static struct s3c2410_platform_i2c tiny4412_i2c3_data __initdata { 10: .flags 0, 11: .bus_num 3, 12: .slave_addr 0x10, 13: .frequency 200*1000, 14: .sda_delay 100, 15: }; 16: 17: static struct i2c_board_info i2c_devs3[] __initdata { 18: { 19: I2C_BOARD_INFO(mma7660, 0x4c), 20: .platform_data mma7660_pdata, 21: }, 22: }; 23: 24: static void __init smdk4x12_machine_init(void) 25: { 26: ... ... 27: s3c_i2c3_set_platdata(tiny4412_i2c3_data); 28: i2c_register_board_info(3, i2c_devs3, ARRAY_SIZE(i2c_devs3)); // 注册板级信息 29: ... ... 30: } 其中 从上面的信息我们可以知道 MMA7660的器件地址是0x4cI2C3的CLK信号新的频率为200KHz。这两个信息比较重要。MMA7660的驱动程序是linux-3.0.86/drivers/hwmon/mma7660.c。 I2C的板级信息 在arch/arm/plat-samsung/dev-i2c3.c中 1: /* linux/arch/arm/plat-samsung/dev-i2c3.c 2: * 3: * Copyright (c) 2010 Samsung Electronics Co., Ltd. 4: * http://www.samsung.com/ 5: * 6: * S5P series device definition for i2c device 3 7: * 8: * This program is free software; you can redistribute it and/or modify 9: * it under the terms of the GNU General Public License version 2 as 10: * published by the Free Software Foundation. 11: */ 12: 13: #include linux/gfp.h 14: #include linux/kernel.h 15: #include linux/string.h 16: #include linux/platform_device.h 17: 18: #include mach/irqs.h 19: #include mach/map.h 20: 21: #include plat/regs-iic.h 22: #include plat/iic.h 23: #include plat/devs.h 24: #include plat/cpu.h 25: 26: static struct resource s3c_i2c_resource[] { 27: [0] { 28: .start S3C_PA_IIC3, 29: .end S3C_PA_IIC3 SZ_4K - 1, 30: .flags IORESOURCE_MEM, 31: }, 32: [1] { 33: .start IRQ_IIC3, 34: .end IRQ_IIC3, 35: .flags IORESOURCE_IRQ, 36: }, 37: }; 38: 39: struct platform_device s3c_device_i2c3 { 40: .name s3c2440-i2c, 41: .id 3, 42: .num_resources ARRAY_SIZE(s3c_i2c_resource), 43: .resource s3c_i2c_resource, 44: }; 45: 46: void __init s3c_i2c3_set_platdata(struct s3c2410_platform_i2c *pd) 47: { 48: struct s3c2410_platform_i2c *npd; 49: 50: if (!pd) { 51: pd default_i2c_data; 52: pd-bus_num 3; 53: } 54: 55: npd s3c_set_platdata(pd, sizeof(struct s3c2410_platform_i2c), 56: s3c_device_i2c3); 57: 58: if (!npd-cfg_gpio) 59: npd-cfg_gpio s3c_i2c3_cfg_gpio; 60: } 然后会在arch/arm/mach-exynos/mach-tiny4412.c中注册 1: static struct platform_device *smdk4x12_devices[] __initdata { 2: ... ... 3: s3c_device_i2c3, 4: ... ... 5: } 6: 7: static void __init smdk4x12_machine_init(void) 8: { 9: ... ... 10: platform_add_devices(smdk4x12_devices, ARRAY_SIZE(smdk4x12_devices)); 11: ... ... 12: } I2C控制器对应的驱动是linux-3.0.86/drivers/i2c/busses/i2c-s3c2410.c。 三、移植 1、首先把MMA7660和I2C控制器的板级信息转化为设备树的形式修改arch/arm/boot/dts/exynos4412-tiny4412.dts添加MMA7660和I2C的硬件信息可以参考内核文档Documentation/devicetree/bindings/i2c/i2c.txt和Documentation/devicetree/bindings/i2c/i2c-s3c2410.txt中断资源的填写可以参考内核文档Documentation/devicetree/bindings/pinctrl/samsung-pinctrl.txt。 1: /* MMA7660FC */ 2: i2c_3 { 3: samsung,i2c-sda-delay 100; 4: samsung,i2c-slave-addr 0x10; 5: samsung,i2c-max-bus-freq 200000; 6: pinctrl-0 i2c3_bus; 7: pinctrl-names default; 8: status okay; 9: 10: mma76604c { 11: compatible freescale,mma7660; 12: reg 0x4c; 13: interrupt-parent gpx3; 14: interrupts 1 2; 15: poll_interval 100; 16: input_fuzz 4; 17: input_flat 4; 18: status okay; 19: }; 20: }; 上面的信息基本上是把原来的板级信息搬过来。 第13行和第14行是设置中断资源参考Documentation/devicetree/bindings/pinctrl/samsung-pinctrl.txt External GPIO and Wakeup Interrupts: The controller supports two types of external interrupts over gpio. The first is the external gpio interrupt and second is the external wakeup interrupts. The difference between the two is that the external wakeup interrupts can be used as system wakeup events. A. External GPIO Interrupts: For supporting external gpio interrupts, the following properties should be specified in the pin-controller device node. - interrupt-parent: phandle of the interrupt parent to which the external GPIO interrupts are forwarded to. - interrupts: interrupt specifier for the controller. The format and value of the interrupt specifier depends on the interrupt parent for the controller. In addition, following properties must be present in node of every bank of pins supporting GPIO interrupts: - interrupt-controller: identifies the controller node as interrupt-parent. - #interrupt-cells: the value of this property should be 2. - First Cell: represents the external gpio interrupt number local to the external gpio interrupt space of the controller. - Second Cell: flags to identify the type of the interrupt - 1 rising edge triggered - 2 falling edge triggered - 3 rising and falling edge triggered - 4 high level triggered - 8 low level triggered 对于interrupts 1 2其中1表示GPX3_12表示的是下降沿触发。 第2行的i2c_3是一个标号i2c3的其他信息是在arch/arm/boot/dts/exynos4.dtsi中 1: i2c_3: i2c13890000 { 2: #address-cells 1; 3: #size-cells 0; 4: compatible samsung,s3c2440-i2c; 5: reg 0x13890000 0x100; 6: interrupts 0 61 0; 7: clocks clock CLK_I2C3; 8: clock-names i2c; 9: pinctrl-names default; 10: pinctrl-0 i2c3_bus; 11: status disabled; 12: }; 第10行是设置GPIO的功能复用i2c3_bus是在文件arch/arm/boot/dts/exynos4x12-pinctrl.dtsi中 1: i2c3_bus: i2c3-bus { 2: samsung,pins gpa1-2, gpa1-3; 3: samsung,pin-function 3; 4: samsung,pin-pud 3; 5: samsung,pin-drv 0; 6: }; 那么是在什么时候解析这部分然后设置功能复用的呢这个以后再说。 2、填写完板级信息接下来就要移植驱动程序了其中I2C控制器的驱动程序Linux内核已经写好了就是drivers/i2c/busses/i2c-s3c2410.c。MMA7660的驱动程序就需要我们自己移植了。 注册 1: static const struct i2c_device_id mma7660_ids[] { 2: { mma7660, 0 }, 3: { }, 4: }; 5: MODULE_DEVICE_TABLE(i2c, mma7660_ids); 6: 7: #ifdef CONFIG_OF 8: static const struct of_device_id mma7660_dt_match[] { 9: { .compatible freescale,mma7660 }, 10: { } 11: }; 12: MODULE_DEVICE_TABLE(of, mma7660_dt_match); 13: #endif 14: 15: static struct i2c_driver mma7660_driver { 16: .driver { 17: .name MMA7660_NAME, 18: .pm mma7660_pm_ops, 19: .of_match_table of_match_ptr(mma7660_dt_match), 20: }, 21: .probe mma7660_probe, 22: .remove mma7660_remove, 23: .id_table mma7660_ids, 24: }; 25: 26: module_i2c_driver(mma7660_driver); 解析设备树 1: static struct mma7660_platform_data *mma7660_parse_dt(struct device *dev) 2: { 3: struct mma7660_platform_data *pdata; 4: struct device_node *np dev-of_node; 5: 6: if (!np) 7: return NULL; 8: 9: pdata devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); 10: if (!pdata) { 11: dev_err(dev, failed to allocate platform data\n); 12: return NULL; 13: } 14: 15: if (of_property_read_u32(np, poll_interval, pdata-poll_interval)) { 16: dev_err(dev, failed to get poll_interval property\n); 17: return NULL; 18: } 19: 20: if (of_property_read_u32(np, input_fuzz, pdata-input_fuzz)) { 21: dev_err(dev, failed to get input_fuzz property\n); 22: return NULL; 23: } 24: 25: if (of_property_read_u32(np, input_flat, pdata-input_flat)) { 26: dev_err(dev, failed to get input_flat property\n); 27: return NULL; 28: } 29: 30: return pdata; 31: } 关于这部分我已经把代码上传到github上了下载方法 git clone https://github.com/pengdonglin137/linux-4.4_tiny4412.git -b port_to_tiny4412 测试 1: [roottiny4412 root]# cd /sys/bus/i2c/devices/3-004c/ 2: [roottiny4412 3-004c]# ls 3: all_axis_g input of_node subsystem x_axis_g 4: driver modalias power tilt_status y_axis_g 5: hwmon name registers uevent z_axis_g 6: [roottiny4412 3-004c]# cat all_axis_g 7: 2, 0, 22 8: [roottiny4412 3-004c]# cat registers 9: REG: 0x00 0x03 ...... [ 0000 0011 ] 10: REG: 0x01 0x01 ...... [ 0000 0001 ] 11: REG: 0x02 0x16 ...... [ 0001 0110 ] 12: REG: 0x03 0x01 ...... [ 0000 0001 ] 13: REG: 0x04 0x02 ...... [ 0000 0010 ] 14: REG: 0x05 0xa0 ...... [ 1010 0000 ] 15: REG: 0x06 0xe7 ...... [ 1110 0111 ] 16: REG: 0x07 0x59 ...... [ 0101 1001 ] 17: REG: 0x08 0x49 ...... [ 0100 1001 ] 18: REG: 0x09 0x04 ...... [ 0000 0100 ] 19: REG: 0x0a 0x0f ...... [ 0000 1111 ] 用hexdump看看上报的事件 1: [roottiny4412 ]# hexdump /dev/input/event0 2: 0000000 0013 0000 9b6a 0001 0003 0002 0015 0000 3: 0000010 0013 0000 9b6a 0001 0000 0000 0000 0000 4: 0000020 0013 0000 4015 0009 0003 0000 0002 0000 5: 0000030 0013 0000 4015 0009 0000 0000 0000 0000 6: 0000040 0018 0000 c6b5 000a 0003 0000 0004 0000 7: 0000050 0018 0000 c6b5 000a 0000 0000 0000 0000 8: 0000060 0019 0000 9ef7 0001 0003 0000 0006 0000 9: 0000070 0019 0000 9ef7 0001 0000 0000 0000 0000 10: 0000080 0019 0000 c6b3 000a 0003 0000 0005 0000 11: 0000090 0019 0000 c6b3 000a 0000 0000 0000 0000 12: 00000a0 0019 0000 d3f0 000d 0003 0000 0004 0000 13: 00000b0 0019 0000 d3f0 000d 0000 0000 0000 0000 14: 00000c0 001a 0000 25c1 0003 0003 0000 0003 0000 15: 00000d0 001a 0000 25c1 0003 0000 0000 0000 0000 16: 00000e0 001a 0000 32d0 0006 0003 0000 0002 0000 17: 00000f0 001a 0000 32d0 0006 0000 0000 0000 0000 18: 0000100 001a 0000 b980 0007 0003 0000 0001 0000 19: 0000110 001a 0000 b980 0007 0000 0000 0000 0000 未完待续… 转载于:https://www.cnblogs.com/pengdonglin137/p/5240416.html
