/**********************************************************************************************                           TI AM335x Linux MUX hacking*  声明：*      1. 本文主要是对TI的AM335x Linux驱动中的引脚复用配置代码进行跟踪；*      2. 参考书籍：AM335x ARM® Cortex™-A8 Microprocessors (MPUs) Technical Reference Manual**                                             2015-6-25 阵雨 深圳 南山平山村 曾剑锋*********************************************************************************************/\\\\\\\\\\\\\-*- 目录 -*-/| 一、跟踪板级文件：                 | 二、跟踪am335x_evm_init()函数：    | 三、跟踪board_mux参数：            | 四、跟踪am33xx_mux_init()函数：    | 五、跟踪am33xx_muxmodes参数：     | 六、跟踪omap_mux_init()函数：      | 七、跟踪omap_mux_init_list()函数： | 八、跟踪omap_mux_init_signals函数：\\\\\\\\\\\\\\\\\\\\//
一、跟踪板级文件：......MACHINE_START(AM335XEVM, "am335xevm")/* Maintainer: Texas Instruments */.atag_offset    = 0x100,.map_io     = am335x_evm_map_io,.init_early = am33xx_init_early,.init_irq   = ti81xx_init_irq,.handle_irq     = omap3_intc_handle_irq,.timer      = &omap3_am33xx_timer,.init_machine   = am335x_evm_init,          // 跟踪该函数MACHINE_END                                            ^|MACHINE_START(AM335XIAEVM, "am335xiaevm")              |/* Maintainer: Texas Instruments */                |.atag_offset    = 0x100,                           |.map_io     = am335x_evm_map_io,                   |.init_irq   = ti81xx_init_irq,                     |.init_early = am33xx_init_early,                   |.timer      = &omap3_am33xx_timer,                 |.init_machine   = am335x_evm_init,    -------------+MACHINE_END二、跟踪am335x_evm_init()函数：static void __init am335x_evm_init(void){am33xx_cpuidle_init();am33xx_mux_init(board_mux);         // 跟踪函数、参数
        omap_serial_init();am335x_evm_i2c_init();omap_sdrc_init(NULL, NULL);usb_musb_init(&musb_board_data);omap_board_config = am335x_evm_config;omap_board_config_size = ARRAY_SIZE(am335x_evm_config);/* Create an alias for icss clock */if (clk_add_alias("pruss", NULL, "pruss_uart_gclk", NULL))pr_warn("failed to create an alias: icss_uart_gclk --> pruss\n");/* Create an alias for gfx/sgx clock */if (clk_add_alias("sgx_ck", NULL, "gfx_fclk", NULL))pr_warn("failed to create an alias: gfx_fclk --> sgx_ck\n");} 三、跟踪board_mux参数：1. 跟踪board_mux[]数组：static struct omap_board_mux board_mux[] __initdata = {/** Setting SYSBOOT[5] should set xdma_event_intr0 pin to mode 3 thereby* allowing clkout1 to be available on xdma_event_intr0.* However, on some boards (like EVM-SK), SYSBOOT[5] isn't properly* latched.* To be extra cautious, setup the pin-mux manually.* If any modules/usecase requries it in different mode, then subsequent* module init call will change the mux accordingly.** 参考书籍：AM335x ARM® Cortex™-A8 Microprocessors (MPUs) Technical Reference Manual -- 760页* --------------------------------------------------------------------* | Offset | Acronym               | Register | Description Section  |* --------------------------------------------------------------------* | 9B0h   | conf_xdma_event_intr0 |          | Section 9.3.51       |* --------------------------------------------------------------------* 观察上面的内容和接下来要配置引脚，我们只需要将Acronym中的conf_前缀去掉，* 然后将剩下的字符串大写，就能配置对应的引脚了，如：*      1. conf_xdma_event_intr0*      2. xdma_event_intr0*      3. XDMA_EVENT_INTR0*                 |*                 |*/                VAM33XX_MUX(XDMA_EVENT_INTR0, OMAP_MUX_MODE3 | AM33XX_PIN_OUTPUT), // 跟踪宏AM33XX_MUX(I2C0_SDA, OMAP_MUX_MODE0 | AM33XX_SLEWCTRL_SLOW |AM33XX_INPUT_EN | AM33XX_PIN_OUTPUT),AM33XX_MUX(I2C0_SCL, OMAP_MUX_MODE0 | AM33XX_SLEWCTRL_SLOW |AM33XX_INPUT_EN | AM33XX_PIN_OUTPUT),{ .reg_offset = OMAP_MUX_TERMINATOR }, //后面的程序通过判断这个表示来结束注册
        };2. 跟踪struct omap_board_mux结构体：/**  * struct omap_board_mux - data for initializing mux registers* @reg_offset: mux register offset from the mux base* @mux_value:  desired mux value to set */          struct omap_board_mux {u16 reg_offset;u16 value;};3. 跟踪AM33XX_MUX()宏：/* If pin is not defined as input, pull would get disabled.* If defined as input, flags supplied will determine pull on/off.*/  // 以此为例：//     AM33XX_MUX(XDMA_EVENT_INTR0, OMAP_MUX_MODE3 | AM33XX_PIN_OUTPUT)//// .reg_offset = (AM33XX_CONTROL_PADCONF_XDMA_EVENT_INTR0_OFFSET) // 跟踪宏   // .value      = (((OMAP_MUX_MODE3 | AM33XX_PIN_OUTPUT) & AM33XX_INPUT_EN) \//               ? (OMAP_MUX_MODE3 | AM33XX_PIN_OUTPUT) \//               : ((mux_value) | AM33XX_PULL_DISA)) #define AM33XX_MUX(mode0, mux_value)                    \{                                   \.reg_offset = (AM33XX_CONTROL_PADCONF_##mode0##_OFFSET),    \.value      = (((mux_value) & AM33XX_INPUT_EN) ? (mux_value)\: ((mux_value) | AM33XX_PULL_DISA)),    \}4. 跟踪模式宏声明：/* 34xx mux mode options for each pin. See TRM for options */#define OMAP_MUX_MODE0      0#define OMAP_MUX_MODE1      1#define OMAP_MUX_MODE2      2#define OMAP_MUX_MODE3      3#define OMAP_MUX_MODE4      4#define OMAP_MUX_MODE5      5#define OMAP_MUX_MODE6      6#define OMAP_MUX_MODE7      75. 跟踪输出宏声明：/* Definition of output pin could have pull disabled, but* this has not been done due to two reasons* 1. AM33XX_MUX will take care of it* 2. If pull was disabled for out macro, combining out & in pull on macros*    would disable pull resistor and AM33XX_MUX cannot take care of the*    correct pull setting and unintentionally pull would get disabled*/#define AM33XX_PIN_OUTPUT       (0)6. 跟踪引脚配置偏移宏，并对比数据手册：// 参考书籍：AM335x ARM® Cortex™-A8 Microprocessors (MPUs) Technical Reference Manual -- 760页// -----------------------------------------------------------------------// | Offset | Acronym               | Register   |  Description Section  |// +--------+-----------------------+------------+-----------------------+// | 9B0h   | conf_xdma_event_intr0 |            |  Section 9.3.51       |// -----------------------------------------------------------------------#define AM33XX_CONTROL_PADCONF_XDMA_EVENT_INTR0_OFFSET      0x09B0四、跟踪am33xx_mux_init()函数：1. 跟踪am33xx_mux_init()函数：int __init am33xx_mux_init(struct omap_board_mux *board_subset){return omap_mux_init("core", 0, AM33XX_CONTROL_PADCONF_MUX_PBASE, // 跟踪参数
                AM33XX_CONTROL_PADCONF_MUX_SIZE, am33xx_muxmodes,NULL, board_subset, NULL);}2. 跟踪AM33XX_CONTROL_PADCONF_MUX_PBASE宏：// 参考书籍：AM335x ARM® Cortex™-A8 Microprocessors (MPUs) Technical Reference  Manual -- 158页// ----------------------------------------------------------------------------------------------------// | Region Name     | Start Address (hex) | End Address (hex)  | Size   |       Description          |// +-----------------+---------------------+--------------------+--------+----------------------------+// | Control Module  |  0x44E1_0000        | 0x44E1_1FFF        | 128KB  |  Control Module Registers  |// ----------------------------------------------------------------------------------------------------#define AM33XX_CONTROL_PADCONF_MUX_PBASE            0x44E10000LU3. 跟踪AM33XX_CONTROL_PADCONF_MUX_SIZE宏：// 参考书籍：AM335x ARM® Cortex™-A8 Microprocessors (MPUs) Technical Reference  Manual -- 761页// 这里的大小没有搞懂，在datasheet中是1444h，而这里是B34h，没搞懂// ----------------------------------------------------------------// | Offset | Acronym           | Register | Description Section  |// +--------+-------------------+----------+----------------------+// | 1444h  | ddr_data1_ioctrl  |          | Section 9.3.92       |// ----------------------------------------------------------------#define AM33XX_CONTROL_PADCONF_VREFN_OFFSET         0x0B34          #define AM33XX_CONTROL_PADCONF_MUX_SIZE             \(AM33XX_CONTROL_PADCONF_VREFN_OFFSET + 0x4)五、跟踪am33xx_muxmodes参数：1. 跟踪am33xx_muxmodes[]数组：/* AM33XX pin mux super set */static struct omap_mux am33xx_muxmodes[] = {_AM33XX_MUXENTRY(GPMC_AD0, 0,"gpmc_ad0", "mmc1_dat0", NULL, NULL,NULL, NULL, NULL, "gpio1_0"),_AM33XX_MUXENTRY(GPMC_AD1, 0,"gpmc_ad1", "mmc1_dat1", NULL, NULL,NULL, NULL, NULL, "gpio1_1"),_AM33XX_MUXENTRY(GPMC_AD2, 0,"gpmc_ad2", "mmc1_dat2", NULL, NULL,NULL, NULL, NULL, "gpio1_2"),_AM33XX_MUXENTRY(GPMC_AD3, 0,"gpmc_ad3", "mmc1_dat3", NULL, NULL,NULL, NULL, NULL, "gpio1_3"),_AM33XX_MUXENTRY(GPMC_AD4, 0,"gpmc_ad4", "mmc1_dat4", NULL, NULL,NULL, NULL, NULL, "gpio1_4"),......{ .reg_offset = OMAP_MUX_TERMINATOR },  //后面的程序通过判断这个表示来结束注册
        }2. 跟踪struct omap_mux结构体：/*** struct omap_mux - data for omap mux register offset and it's value* @reg_offset: mux register offset from the mux base* @gpio:       GPIO number* @muxnames:   available signal modes for a ball* @balls:      available balls on the package* @partition:  mux partition*/struct omap_mux {u16 reg_offset;u16 gpio;#ifdef CONFIG_OMAP_MUXchar    *muxnames[OMAP_MUX_NR_MODES];#ifdef CONFIG_DEBUG_FSchar    *balls[OMAP_MUX_NR_SIDES];#endif   #endif}; 2. 跟踪_AM33XX_MUXENTRY宏：//// 以此为例：//  _AM33XX_MUXENTRY(GPMC_AD0, 0, "gpmc_ad0", "mmc1_dat0", NULL, NULL, NULL, NULL, NULL, "gpio1_0")//  // .reg_offset = AM33XX_CONTROL_PADCONF_GPMC_AD0_OFFSET // .gpio       = 0      // 相当于取下面muxnames中的第0个// .muxnames   = {"gpmc_ad0", "mmc1_dat0", NULL, NULL, NULL, NULL, NULL, "gpio1_0"}#define _AM33XX_MUXENTRY(M0, g, m0, m1, m2, m3, m4, m5, m6, m7)     \{                                   \.reg_offset = (AM33XX_CONTROL_PADCONF_##M0##_OFFSET),   \.gpio       = (g),                      \.muxnames   = { m0, m1, m2, m3, m4, m5, m6, m7 },       \}3. 跟踪AM33XX_CONTROL_PADCONF_GPMC_AD0_OFFSET宏，并对比datasheet：// 参考书籍：AM335x ARM® Cortex™-A8 Microprocessors (MPUs) Technical Reference Manual -- 758页// ------------------------------------------------------------------------------------------------------------// | Offset | Acronym        | Register  | Description Section                                                // +--------+----------------+-----------+---------------------------------------------------------------------// | 800h   | conf_gpmc_ad0  |           | See the device datasheet for information on default pin Section 9.3.51// ------------------------------------------------------------------------------------------------------------#define AM33XX_CONTROL_PADCONF_GPMC_AD0_OFFSET          0x0800六、跟踪omap_mux_init()函数：int __init omap_mux_init(const char *name, u32 flags,u32 mux_pbase, u32 mux_size,struct omap_mux *superset,struct omap_mux *package_subset,struct omap_board_mux *board_mux,struct omap_ball *package_balls){struct omap_mux_partition *partition;partition = kzalloc(sizeof(struct omap_mux_partition), GFP_KERNEL);if (!partition)return -ENOMEM;partition->name = name;                             // 分区的意思相当于模块的意思partition->flags = flags;partition->size = mux_size;partition->phys = mux_pbase;partition->base = ioremap(mux_pbase, mux_size);     // 重新映射IO地址if (!partition->base) {pr_err("%s: Could not ioremap mux partition at 0x%08x\n",__func__, partition->phys);kfree(partition);return -ENODEV;}INIT_LIST_HEAD(&partition->muxmodes);               // 初始化分区头结点链表
    list_add_tail(&partition->node, &mux_partitions);   // 将分区加入分区链表mux_partitions_cnt++;                               // 分区总数统计pr_info("%s: Add partition: #%d: %s, flags: %x\n", __func__,mux_partitions_cnt, partition->name, partition->flags);omap_mux_init_package(superset, package_subset, package_balls); // 两个都是nullomap_mux_init_list(partition, superset);                        // 跟踪函数omap_mux_init_signals(partition, board_mux);                    // 跟踪函数return 0;}七、跟踪omap_mux_init_list()函数：1. 跟踪omap_mux_init_list()函数:/** Note if CONFIG_OMAP_MUX is not selected, we will only initialize* the GPIO to mux offset mapping that is needed for dynamic muxing* of GPIO pins for off-idle.*/static void __init omap_mux_init_list(struct omap_mux_partition *partition,struct omap_mux *superset){while (superset->reg_offset !=  OMAP_MUX_TERMINATOR) {struct omap_mux *entry;// 去掉一些不符合要求的的配置引脚
        #ifdef CONFIG_OMAP_MUXif (!superset->muxnames || !superset->muxnames[0]) {superset++;continue;}#else/* Skip pins that are not muxed as GPIO by bootloader */if (!OMAP_MODE_GPIO(omap_mux_read(partition,superset->reg_offset))) {superset++;continue;}#endifentry = omap_mux_list_add(partition, superset);if (!entry) {pr_err("%s: Could not add entry\n", __func__);return;}superset++;}}2. 跟踪omap_mux_list_add()函数：static struct omap_mux * __init omap_mux_list_add(struct omap_mux_partition *partition,struct omap_mux *src){struct omap_mux_entry *entry;struct omap_mux *m;entry = kzalloc(sizeof(struct omap_mux_entry), GFP_KERNEL);if (!entry)return NULL;m = &entry->mux;entry->mux = *src;#ifdef CONFIG_OMAP_MUXif (omap_mux_copy_names(src, m)) {      // 将数据另存的感觉
                kfree(entry);return NULL;}#endifmutex_lock(&muxmode_mutex);list_add_tail(&entry->node, &partition->muxmodes);      // 将节点放入分区节点链表中mutex_unlock(&muxmode_mutex);return m;}3. 跟踪omap_mux_copy_names()函数:// 这个函数的大概意思也就是转存的感觉static int __init omap_mux_copy_names(struct omap_mux *src,struct omap_mux *dst){int i;for (i = 0; i < OMAP_MUX_NR_MODES; i++) {if (src->muxnames[i]) {dst->muxnames[i] = kstrdup(src->muxnames[i],GFP_KERNEL);if (!dst->muxnames[i])goto free;}}#ifdef CONFIG_DEBUG_FSfor (i = 0; i < OMAP_MUX_NR_SIDES; i++) {if (src->balls[i]) {dst->balls[i] = kstrdup(src->balls[i], GFP_KERNEL);if (!dst->balls[i])goto free;}}#endifreturn 0;free:omap_mux_free_names(dst);return -ENOMEM;}八、跟踪omap_mux_init_signals函数：1. 跟踪omap_mux_init_signals()函数：static void omap_mux_init_signals(struct omap_mux_partition *partition,struct omap_board_mux *board_mux){omap_mux_set_cmdline_signals();             // 不知道这里是干啥的，不跟踪omap_mux_write_array(partition, board_mux); // 跟踪该函数
        }2. 跟踪omap_mux_write_array()函数：void omap_mux_write_array(struct omap_mux_partition *partition,struct omap_board_mux *board_mux){if (!board_mux)return;while (board_mux->reg_offset != OMAP_MUX_TERMINATOR) {omap_mux_write(partition, board_mux->value,  // 跟踪函数board_mux->reg_offset);board_mux++;}}3. 跟踪am33xx_mux_init()函数：/** int __init am33xx_mux_init(struct omap_board_mux *board_subset)*  {   *      return omap_mux_init("core", 0 /* flag = 0 */, AM33XX_CONTROL_PADCONF_MUX_PBASE,*              AM33XX_CONTROL_PADCONF_MUX_SIZE, am33xx_muxmodes,*              NULL, board_subset, NULL);*  } */void omap_mux_write(struct omap_mux_partition *partition, u16 val,u16 reg){if (partition->flags & OMAP_MUX_REG_8BIT)__raw_writeb(val, partition->base + reg);else__raw_writew(val, partition->base + reg);}4. 跟踪OMAP_MUX_REG_8BIT宏：/*              * omap_mux_init flags definition:*   * OMAP_MUX_REG_8BIT: Ensure that access to padconf is done in 8 bits.* The default value is 16 bits.* OMAP_MUX_GPIO_IN_MODE3: The GPIO is selected in mode3.* The default is mode4.*/#define OMAP_MUX_REG_8BIT       (1 << 0)