How to write Platform Devices and Drivers with FPGA via GPMC
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本文讨论了如何通过通用内存控制器 (GPMC) 使用 FPGA 编写平台设备和驱动程序。文档详细介绍了平台设备和驱动的结构、驱动模型的标准以及设备绑定的过程。最后，提到将有关 GPMC 的配置和示例代码的重要性，以确保正确实现和避免内核恐慌。
![Supported Devices .GPMC_CONFIG1_i[11:10] Access Size Adaptation and Device Width .GPMC_CONFIG1_i[13:12]](https://image.slidesharecdn.com/howtowriteplatformdevicesanddrivers-110615093011-phpapp01/85/How-to-write-Platform-Devices-and-Drivers-with-FPGA-via-GPMC-17-320.jpg)
![結論 Platform Device 和 Platform Driver 區別？ GPMC Config_[1-7] 設定方式及規範 實際參考 NAND Driver 程式](https://image.slidesharecdn.com/howtowriteplatformdevicesanddrivers-110615093011-phpapp01/85/How-to-write-Platform-Devices-and-Drivers-with-FPGA-via-GPMC-20-320.jpg)
How to write Platform Devices and Drivers with FPGA via GPMC
- 1. How to write Platform Devices and Drivers with FPGA via GPMC Bo-Yi Wu 2011.06.15 http://blog.wu-boy.com
- 2. What’s GPMC 全名 General-Purpose Memory Controller the device unified memory controller (UMC) dedicated to interfacing external memory devices. NAND Flash NOR Flash FPGA (*) 如果要更深入研究，請參考 TI 線上 Documentation
- 3. 寫 GPMC Drive 跟 FPGA 溝通前
- 4. 必須先瞭解什麼是 Platform Devices 和 Platform Drivers
- 5. 撰寫 Driver Model 事先預備 Porting Drivers to New Driver Model Driver Binding Bus Types Device Classes Basic Device Structure Managed Device Resource Device Drivers Device Interfaces Platform Devices and Drivers
- 6. Platform 架構 參考 <linux/platform_device.h> 來瞭解 driver model 如何跟 platform bus 溝通 用在 system-on-chip processors 或者是一些 "legacy" PC interconnects
- 7. Platform devices 請指定一個名稱用來 Driver Binding ，以及定義該 Devices 需要用到的 addresses 和 IRQs. struct platform_device { const char *name; u32 id; struct device dev; u32 num_resources; struct resource *resource; };
- 8. Platform drivers Platform drivers 走 Driver Model 標準規範，提供 probe 及 remove method ，它們提供 power 管理及關閉提醒等標準
- 9. struct platform_driver { int (*probe)(struct platform_device *); int (*remove)(struct platform_device *); void (*shutdown)(struct platform_device *); int (*suspend)(struct platform_device *, pm_message_t state); int (*suspend_late)(struct platform_device *, pm_message_t state); int (*resume_early)(struct platform_device *); int (*resume)(struct platform_device *); struct device_driver driver; };
- 10. Probe 用來偵測特定 Hardware 是否存在，及使用該裝置資源 (clocks 和 device platform_data) 透過底下函式來註冊 Driver int platform_driver_register(struct platform_driver *drv); 過去 Legacy Driver 並不會完全遵守標準 driver model ，這些 driver 會去註冊自己的 platform device ，而不是讓系統來完成註冊
- 11. 裝置初始化 在大多數的 Platform 設備都必須先註冊 Platform Device 定義 platform_data, resource, 共有多少個 resource 等等 platform_device_register platform_add_devices
- 12. Device Naming 和 Driver Binding platform_device.dev.bus_id 是一個 device id 分為兩個 component: platform_device.name 用來跟 Driver match platform_device.id 裝置編號順序 ( 例如假設有支援多個 NAND 或 NOR Flash) ，如果設定為 -1 表示為獨一無二的裝置
- 13. Driver binding 在 Driver Core 裡面透過 probe 自動匹對 利用 Device Name and ID 去 match name/id: gpmc_bus.1 或 gpmc_bus
- 14. board-omap3evm GPMC Device Init Match Driver name GPMC Driver Init GPMC Address IRQ GPMC Clock and Chip Select Define
- 15. GPMC support functions gpmc_cs_read_reg gpmc_cs_write_reg Please referrer arch/arm/mach-omap2/gpmc.c
- 17. Supported Devices .GPMC_CONFIG1_i[11:10] Access Size Adaptation and Device Width .GPMC_CONFIG1_i[13:12]
- 18. Timing Setting
- 20. 結論 Platform Device 和 Platform Driver 區別？ GPMC Config_[1-7] 設定方式及規範 實際參考 NAND Driver 程式