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am335x 自身的 uart 驱动集成在 kernel 的 arch/arm/mach-omap2/ 里面。
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文件是 arch/arm/mach-omap2/serial.c
// 看到最底部 omap_serial_init 入口函数。
void __init omap_serial_init(void)
{
omap_serial_board_init(NULL); // ---> 1.0
}
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1.0 omap_serial_board_init
void __init omap_serial_board_init(struct omap_uart_port_info *info)
{
struct omap_uart_state *uart; // ---> 1.1
struct omap_board_data bdata; // ---> 1.1
// 这里是轮询所有 uart ，并配置基本的属性一下
// 在这里，我们主要要弄懂 uart_list 是怎么来的，在哪里被初始化
list_for_each_entry(uart, &uart_list, node) {
bdata.id = uart->num;
bdata.flags = 0;
bdata.pads = NULL;
bdata.pads_cnt = 0;
if (cpu_is_omap44xx() || (cpu_is_omap34xx() &&
!cpu_is_am33xx()))
omap_serial_fill_default_pads(&bdata);
if (!info)
omap_serial_init_port(&bdata, NULL); // ---> 2.0
else
omap_serial_init_port(&bdata, &info[uart->num]);
}
}
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1.1 struct omap_uart_state 和 struct omap_board_data
// arch/arm/mach-omap2/serial.c
//
struct omap_uart_state {
int num;
int can_sleep;
struct list_head node;
struct omap_hwmod *oh;
struct platform_device *pdev;
};
// arch/arm/mach-omap2/mux.h
// struct omap_board_data - board specific device data
struct omap_board_data {
int id;
u32 flags;
struct omap_device_pad *pads;
int pads_cnt;
};
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2.0 omap_serial_init_port
void __init omap_serial_init_port(struct omap_board_data *bdata,
struct omap_uart_port_info *info)
{
struct omap_uart_state *uart;
struct omap_hwmod *oh;
struct platform_device *pdev;
void *pdata = NULL;
u32 pdata_size = 0;
char *name;
struct omap_uart_port_info omap_up;
if (WARN_ON(!bdata))
return;
if (WARN_ON(bdata->id < 0))
return;
if (WARN_ON(bdata->id >= num_uarts))
return;
list_for_each_entry(uart, &uart_list, node)
if (bdata->id == uart->num)
break;
if (!info)
info = omap_serial_default_info;
oh = uart->oh;
name = DRIVER_NAME;
omap_up.dma_enabled = info->dma_enabled;
omap_up.uartclk = OMAP24XX_BASE_BAUD * 16;
omap_up.flags = UPF_BOOT_AUTOCONF;
omap_up.get_context_loss_count = omap_pm_get_dev_context_loss_count;
omap_up.set_forceidle = omap_uart_set_forceidle;
omap_up.set_noidle = omap_uart_set_noidle;
omap_up.enable_wakeup = omap_uart_enable_wakeup;
omap_up.dma_rx_buf_size = info->dma_rx_buf_size;
omap_up.dma_rx_timeout = info->dma_rx_timeout;
omap_up.dma_rx_poll_rate = info->dma_rx_poll_rate;
omap_up.autosuspend_timeout = info->autosuspend_timeout;
/* Enable the MDR1 Errata i202 for OMAP2430/3xxx/44xx */
if (!cpu_is_omap2420() && !cpu_is_ti816x())
omap_up.errata |= UART_ERRATA_i202_MDR1_ACCESS;
/* Enable DMA Mode Force Idle Errata i291 for omap34xx/3630 */
if ((cpu_is_omap34xx() || cpu_is_omap3630()) && !cpu_is_am33xx())
omap_up.errata |= UART_ERRATA_i291_DMA_FORCEIDLE;
pdata = &omap_up;
pdata_size = sizeof(struct omap_uart_port_info);
if (WARN_ON(!oh))
return;
pdev = omap_device_build(name, uart->num, oh, pdata, pdata_size,
NULL, 0, false);
WARN(IS_ERR(pdev), "Could not build omap_device for %s: %s.
",
name, oh->name);
if ((console_uart_id == bdata->id) && no_console_suspend)
omap_device_disable_idle_on_suspend(pdev);
oh->mux = omap_hwmod_mux_init(bdata->pads, bdata->pads_cnt);
uart->pdev = pdev;
oh->dev_attr = uart;
if (((cpu_is_omap34xx() || cpu_is_omap44xx()) && bdata->pads)
&& !uart_debug)
device_init_wakeup(&pdev->dev, true);
}