目前主流的Uboot启动模式分为三级启动:
大致启动过程如下(32位ARM):
arch\arm\lib\crt0.S
...
bl board_init_f
...
ldr pc, =board_init_r /* this is auto-relocated! */
...
board_init_f
会完成串口以及DRAM的初始化,以及必要的板级设备初始化
arch\arm\mach-sunxi\board.c
void board_init_f(ulong dummy)
{
spl_init();
//串口初始化
preloader_console_init();
#ifdef CONFIG_SPL_I2C_SUPPORT
/* Needed early by sunxi_board_init if PMU is enabled */
i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);
#endif
//必要的板级设备以及DRAM初始化
sunxi_board_init();
//内存测试
#ifdef CONFIG_SPL_BUILD
spl_mem_test();
#endif
}
common\spl\spl.c
void board_init_r(gd_t *dummy1, ulong dummy2)
{
u32 spl_boot_list[] = {
BOOT_DEVICE_NONE,
BOOT_DEVICE_NONE,
BOOT_DEVICE_NONE,
BOOT_DEVICE_NONE,
BOOT_DEVICE_NONE,
};
struct spl_image_info spl_image;
debug(">>spl:board_init_r()\n");
...
//选择BOOT设备(MMC,NAND,NOR等)
board_boot_order(spl_boot_list);
//从FLASH介质中读取UBOOT完整代码段到DRAM
if (boot_from_devices(&spl_image, spl_boot_list,
ARRAY_SIZE(spl_boot_list))) {
puts("SPL: failed to boot from all boot devices\n");
hang();
}
spl_image.entry_point |= 0x1;
//根据读取的代码段,确认代码段是UBOOT还是KERNEL
switch (spl_image.os) {
case IH_OS_U_BOOT:
debug("Jumping to U-Boot\n");
break;
case IH_OS_LINUX:
debug("Jumping to Linux\n");
spl_fixup_fdt();
spl_board_prepare_for_linux();
jump_to_image_linux(&spl_image);
default:
debug("Unsupported OS image.. Jumping nevertheless..\n");
}
...
//跳转到UBOOT执行
debug("loaded - jumping to U-Boot...\n");
spl_board_prepare_for_boot();
jump_to_image_no_args(&spl_image);
这个章节再关注下board_boot_order
这个函数
common\spl\spl.c
__weak void board_boot_order(u32 *spl_boot_list)
{
spl_boot_list[0] = spl_boot_device();
}
arch\arm\mach-sunxi\board.c
uint32_t sunxi_get_boot_device(void)
{
int boot_source;
/*
* When booting from the SD card or NAND memory, the "eGON.BT0"
* signature is expected to be found in memory at the address 0x0004
* (see the "mksunxiboot" tool, which generates this header).
*
* When booting in the FEL mode over USB, this signature is patched in
* memory and replaced with something else by the 'fel' tool. This other
* signature is selected in such a way, that it can't be present in a
* valid bootable SD card image (because the BROM would refuse to
* execute the SPL in this case).
*
* This checks for the signature and if it is not found returns to
* the FEL code in the BROM to wait and receive the main u-boot
* binary over USB. If it is found, it determines where SPL was
* read from.
*/
if (!is_boot0_magic(SPL_ADDR + 4)) /* eGON.BT0 */
return BOOT_DEVICE_BOARD;
boot_source = readb(SPL_ADDR + 0x28);
printf("boot source %d\n", boot_source);
switch (boot_source) {
case SUNXI_BOOTED_FROM_MMC0:
return BOOT_DEVICE_MMC1;
case SUNXI_BOOTED_FROM_NAND:
return BOOT_DEVICE_NAND;
case SUNXI_BOOTED_FROM_MMC2:
return BOOT_DEVICE_MMC2;
case SUNXI_BOOTED_FROM_SPI:
return BOOT_DEVICE_SPI;
}
panic("Unknown boot source %d\n", boot_source);
return -1; /* Never reached */
}
u32 spl_boot_device(void)
{
return sunxi_get_boot_device();
}
如上就是BOOT的FLASH设备选择过程。
需要注意的是要将sunxi_spi_spl.c
编译进SPL中
common/spl/Makefile/
+obj-y += sunxi_spi_spl.o
代码如下:
/*
* Copyright (C) 2016 Siarhei Siamashka
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include
#include
#include
#include
#include
#ifdef CONFIG_SPL_OS_BOOT
#error CONFIG_SPL_OS_BOOT is not supported yet
#endif
/*
* This is a very simple U-Boot image loading implementation, trying to
* replicate what the boot ROM is doing when loading the SPL. Because we
* know the exact pins where the SPI Flash is connected and also know
* that the Read Data Bytes (03h) command is supported, the hardware
* configuration is very simple and we don't need the extra flexibility
* of the SPI framework. Moreover, we rely on the default settings of
* the SPI controler hardware registers and only adjust what needs to
* be changed. This is good for the code size and this implementation
* adds less than 400 bytes to the SPL.
*
* There are two variants of the SPI controller in Allwinner SoCs:
* A10/A13/A20 (sun4i variant) and everything else (sun6i variant).
* Both of them are supported.
*
* The pin mixing part is SoC specific and only A10/A13/A20/H3/A64 are
* supported at the moment.
*/
/*****************************************************************************/
/* SUN4I variant of the SPI controller */
/*****************************************************************************/
#define SUN4I_SPI0_CCTL (0x01C05000 + 0x1C)
#define SUN4I_SPI0_CTL (0x01C05000 + 0x08)
#define SUN4I_SPI0_RX (0x01C05000 + 0x00)
#define SUN4I_SPI0_TX (0x01C05000 + 0x04)
#define SUN4I_SPI0_FIFO_STA (0x01C05000 + 0x28)
#define SUN4I_SPI0_BC (0x01C05000 + 0x20)
#define SUN4I_SPI0_TC (0x01C05000 + 0x24)
#define SUN4I_CTL_ENABLE BIT(0)
#define SUN4I_CTL_MASTER BIT(1)
#define SUN4I_CTL_TF_RST BIT(8)
#define SUN4I_CTL_RF_RST BIT(9)
#define SUN4I_CTL_XCH BIT(10)
/*****************************************************************************/
/* SUN6I variant of the SPI controller */
/*****************************************************************************/
#define SUN6I_SPI0_CCTL (0x01C68000 + 0x24)
#define SUN6I_SPI0_GCR (0x01C68000 + 0x04)
#define SUN6I_SPI0_TCR (0x01C68000 + 0x08)
#define SUN6I_SPI0_FIFO_STA (0x01C68000 + 0x1C)
#define SUN6I_SPI0_MBC (0x01C68000 + 0x30)
#define SUN6I_SPI0_MTC (0x01C68000 + 0x34)
#define SUN6I_SPI0_BCC (0x01C68000 + 0x38)
#define SUN6I_SPI0_TXD (0x01C68000 + 0x200)
#define SUN6I_SPI0_RXD (0x01C68000 + 0x300)
#define SUN6I_CTL_ENABLE BIT(0)
#define SUN6I_CTL_MASTER BIT(1)
#define SUN6I_CTL_SRST BIT(31)
#define SUN6I_TCR_XCH BIT(31)
/*****************************************************************************/
#define CCM_AHB_GATING0 (0x01C20000 + 0x60)
#define CCM_SPI0_CLK (0x01C20000 + 0xA0)
#define SUN6I_BUS_SOFT_RST_REG0 (0x01C20000 + 0x2C0)
#define AHB_RESET_SPI0_SHIFT 20
#define AHB_GATE_OFFSET_SPI0 20
#define SPI0_CLK_DIV_BY_2 0x1000
#define SPI0_CLK_DIV_BY_4 0x1001
#define _DEBUG 1
#define CONFIG_SYS_SPI_U_BOOT_OFFS 0x8000
/*****************************************************************************/
/*
* Allwinner A10/A20 SoCs were using pins PC0,PC1,PC2,PC23 for booting
* from SPI Flash, everything else is using pins PC0,PC1,PC2,PC3.
*/
static void spi0_pinmux_setup(unsigned int pin_function)
{
unsigned int pin;
for (pin = SUNXI_GPC(0); pin <= SUNXI_GPC(2); pin++)
sunxi_gpio_set_cfgpin(pin, pin_function);
if (IS_ENABLED(CONFIG_MACH_SUN4I) || IS_ENABLED(CONFIG_MACH_SUN7I))
sunxi_gpio_set_cfgpin(SUNXI_GPC(23), pin_function);
else
sunxi_gpio_set_cfgpin(SUNXI_GPC(3), pin_function);
}
/*
* Setup 6 MHz from OSC24M (because the BROM is doing the same).
*/
static void spi0_enable_clock(void)
{
/* Deassert SPI0 reset on SUN6I */
if (IS_ENABLED(CONFIG_SUNXI_GEN_SUN6I))
setbits_le32(SUN6I_BUS_SOFT_RST_REG0,
(1 << AHB_RESET_SPI0_SHIFT));
/* Open the SPI0 gate */
setbits_le32(CCM_AHB_GATING0, (1 << AHB_GATE_OFFSET_SPI0));
/* Divide by 4 */
writel(SPI0_CLK_DIV_BY_4, IS_ENABLED(CONFIG_SUNXI_GEN_SUN6I) ?
SUN6I_SPI0_CCTL : SUN4I_SPI0_CCTL);
/* 24MHz from OSC24M */
writel((1 << 31), CCM_SPI0_CLK);
if (IS_ENABLED(CONFIG_SUNXI_GEN_SUN6I)) {
/* Enable SPI in the master mode and do a soft reset */
setbits_le32(SUN6I_SPI0_GCR, SUN6I_CTL_MASTER |
SUN6I_CTL_ENABLE |
SUN6I_CTL_SRST);
/* Wait for completion */
while (readl(SUN6I_SPI0_GCR) & SUN6I_CTL_SRST)
;
} else {
/* Enable SPI in the master mode and reset FIFO */
setbits_le32(SUN4I_SPI0_CTL, SUN4I_CTL_MASTER |
SUN4I_CTL_ENABLE |
SUN4I_CTL_TF_RST |
SUN4I_CTL_RF_RST);
}
}
static void spi0_disable_clock(void)
{
/* Disable the SPI0 controller */
if (IS_ENABLED(CONFIG_SUNXI_GEN_SUN6I))
clrbits_le32(SUN6I_SPI0_GCR, SUN6I_CTL_MASTER |
SUN6I_CTL_ENABLE);
else
clrbits_le32(SUN4I_SPI0_CTL, SUN4I_CTL_MASTER |
SUN4I_CTL_ENABLE);
/* Disable the SPI0 clock */
writel(0, CCM_SPI0_CLK);
/* Close the SPI0 gate */
clrbits_le32(CCM_AHB_GATING0, (1 << AHB_GATE_OFFSET_SPI0));
/* Assert SPI0 reset on SUN6I */
if (IS_ENABLED(CONFIG_SUNXI_GEN_SUN6I))
clrbits_le32(SUN6I_BUS_SOFT_RST_REG0,
(1 << AHB_RESET_SPI0_SHIFT));
}
static void spi0_init(void)
{
unsigned int pin_function = SUNXI_GPC_SPI0;
if (IS_ENABLED(CONFIG_MACH_SUN50I))
pin_function = SUN50I_GPC_SPI0;
spi0_pinmux_setup(pin_function);
spi0_enable_clock();
}
static void spi0_deinit(void)
{
/* New SoCs can disable pins, older could only set them as input */
unsigned int pin_function = SUNXI_GPIO_INPUT;
if (IS_ENABLED(CONFIG_SUNXI_GEN_SUN6I))
pin_function = SUNXI_GPIO_DISABLE;
spi0_disable_clock();
spi0_pinmux_setup(pin_function);
}
/*****************************************************************************/
#define SPI_READ_MAX_SIZE 60 /* FIFO size, minus 4 bytes of the header */
static void sunxi_spi0_read_data(u8 *buf, u32 addr, u32 bufsize,
ulong spi_ctl_reg,
ulong spi_ctl_xch_bitmask,
ulong spi_fifo_reg,
ulong spi_tx_reg,
ulong spi_rx_reg,
ulong spi_bc_reg,
ulong spi_tc_reg,
ulong spi_bcc_reg)
{
writel(4 + bufsize, spi_bc_reg); /* Burst counter (total bytes) */
writel(4, spi_tc_reg); /* Transfer counter (bytes to send) */
if (spi_bcc_reg)
writel(4, spi_bcc_reg); /* SUN6I also needs this */
/* Send the Read Data Bytes (03h) command header */
writeb(0x03, spi_tx_reg);
writeb((u8)(addr >> 16), spi_tx_reg);
writeb((u8)(addr >> 8), spi_tx_reg);
writeb((u8)(addr), spi_tx_reg);
/* Start the data transfer */
setbits_le32(spi_ctl_reg, spi_ctl_xch_bitmask);
/* Wait until everything is received in the RX FIFO */
while ((readl(spi_fifo_reg) & 0x7F) < 4 + bufsize)
;
/* Skip 4 bytes */
readl(spi_rx_reg);
/* Read the data */
while (bufsize-- > 0)
*buf++ = readb(spi_rx_reg);
/* tSHSL time is up to 100 ns in various SPI flash datasheets */
udelay(1);
}
static void spi0_read_data(void *buf, u32 addr, u32 len)
{
u8 *buf8 = buf;
u32 chunk_len;
while (len > 0) {
chunk_len = len;
if (chunk_len > SPI_READ_MAX_SIZE)
chunk_len = SPI_READ_MAX_SIZE;
if (IS_ENABLED(CONFIG_SUNXI_GEN_SUN6I)) {
sunxi_spi0_read_data(buf8, addr, chunk_len,
SUN6I_SPI0_TCR,
SUN6I_TCR_XCH,
SUN6I_SPI0_FIFO_STA,
SUN6I_SPI0_TXD,
SUN6I_SPI0_RXD,
SUN6I_SPI0_MBC,
SUN6I_SPI0_MTC,
SUN6I_SPI0_BCC);
} else {
sunxi_spi0_read_data(buf8, addr, chunk_len,
SUN4I_SPI0_CTL,
SUN4I_CTL_XCH,
SUN4I_SPI0_FIFO_STA,
SUN4I_SPI0_TX,
SUN4I_SPI0_RX,
SUN4I_SPI0_BC,
SUN4I_SPI0_TC,
0);
}
len -= chunk_len;
buf8 += chunk_len;
addr += chunk_len;
}
}
static ulong spi_load_read(struct spl_load_info *load, ulong sector,
ulong count, void *buf)
{
spi0_read_data(buf, sector, count);
return count;
}
/*****************************************************************************/
static int spl_spi_load_image(struct spl_image_info *spl_image,
struct spl_boot_device *bootdev)
{
int ret = 0;
struct image_header *header;
header = (struct image_header *)(CONFIG_SYS_TEXT_BASE);
spi0_init();
spi0_read_data((void *)header, CONFIG_SYS_SPI_U_BOOT_OFFS, 0x40);
if (IS_ENABLED(CONFIG_SPL_LOAD_FIT) &&
image_get_magic(header) == FDT_MAGIC) {
struct spl_load_info load;
debug("Found FIT image\n");
load.dev = NULL;
load.priv = NULL;
load.filename = NULL;
load.bl_len = 1;
load.read = spi_load_read;
ret = spl_load_simple_fit(spl_image, &load,
CONFIG_SYS_SPI_U_BOOT_OFFS, header);
} else {
ret = spl_parse_image_header(spl_image, header);
if (ret)
return ret;
spi0_read_data((void *)spl_image->load_addr,
CONFIG_SYS_SPI_U_BOOT_OFFS, spl_image->size);
}
spi0_deinit();
return ret;
}
/* Use priorty 0 to override the default if it happens to be linked in */
SPL_LOAD_IMAGE_METHOD("Jon SPI", 0, BOOT_DEVICE_SPI, spl_spi_load_image);
SPL_LOAD_IMAGE_METHOD("Jon SPI", 0, BOOT_DEVICE_SPI, spl_spi_load_image);
如上是SPI BOOT的入口项;另外需要特别留意CONFIG_SYS_SPI_U_BOOT_OFFS,这个是配置的UBOOT代码的偏移地址,如何确定这个偏移是多少呢?这个需要看u-boot-spl.lds
文件配置的是多大了,如下:
u-boot/arch/arm/cpu/armv7/sunxi/u-boot-spl.lds
MEMORY { .sram : ORIGIN = CONFIG_SPL_TEXT_BASE,\
LENGTH = CONFIG_SPL_MAX_SIZE }
MEMORY { .sdram : ORIGIN = CONFIG_SPL_BSS_START_ADDR, \
LENGTH = CONFIG_SPL_BSS_MAX_SIZE }
CONFIG_SYS_SPI_U_BOOT_OFFS=CONFIG_SPL_TEXT_BASE+CONFIG_SPL_MAX_SIZE
其实还可以直接看SPL目录的生成文件:
u-boot/spl/u-boot-spl.lds
MEMORY { .sram : ORIGIN = 0x60, LENGTH = 0x7fa0 }
MEMORY { .sdram : ORIGIN = 0x4ff80000, LENGTH = 0x00080000 }
拔出MMC后启动LOG如下:
U-Boot Jon SPL 2017.11 (Apr 30 2019 - 15:46:34)
DRAM: 256 MiB(408MHz)
CPU Freq: 408MHz
memory test: 1
Pattern 55aa Writing...Reading...OK
>>spl:board_init_r()
boot source 3
flag : 0xffffffff
Trying to boot from Jon SPI
Boot device: untest, may occur error
Jon,spl_parse_image_header
0x27,
0x05,0x19,0x56,0x98,0x4a,0xd2,0x7b,0x5c,0xc7,0xfd,
0x77,0x00,0x04,0xf6,0x2c,0x4a,0x00,0x00,0x00,0x00,
0x00,0x00,0x00,0x34,0x15,0xab,0xdd,0x11,0x02,0x05,
0x00,0x55,0x2d,0x42,0x6f,0x6f,0x74,0x20,0x32,0x30,
0x31,0x37,0x2e,0x31,0x31,0x20,0x66,0x6f,0x72,0x20,
0x73,0x75,0x6e,0x78,0x69,0x20,0x62,0x6f,0x61,0x72,
0x64,0x00,0x00,
spl: payload image: *s load addr: 0x20 size: 1241514016
loader->name : Jon SPI
Jumping to U-Boot
SPL malloc() used lx bytes (0 KB)
loaded - jumping to U-Boot...
image entry point: 0x
U-Boot 2017.11 (Apr 30 2019 - 15:46:34 +0800) Allwinner Technology
CPU: Allwinner H3 (SUN8I 1680)
Model: FriendlyElec NanoPi H3
DRAM: 256 MiB
Detecting eMMC...
No MMC device available
No MMC device available
eMMC not exist
CPU Freq: 1008MHz
MMC: SUNXI SD/MMC: 0, SUNXI SD/MMC: 1
Card did not respond to voltage select!
mmc_init: -95, time 22
*** Warning - MMC init failed, using default environment
ERROR: unsupported boot mmc 3
### ERROR ### Please RESET the board ###
很明显SPL已经能够正常从SPI中BOOT了