/*********************************************************************************************
* 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
* |
* |
*/ V
AM33XX_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 7
5. 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 0x44E10000LU
3. 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_MUX
char *muxnames[OMAP_MUX_NR_MODES];
#ifdef CONFIG_DEBUG_FS
char *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null
omap_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_MUX
if (!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;
}
#endif
entry = 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_MUX
if (omap_mux_copy_names(src, m)) { // 将数据另存的感觉
kfree(entry);
return NULL;
}
#endif
mutex_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_FS
for (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;
}
}
#endif
return 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)
