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linux4.1.36 SPI 时钟找不到 不生成设备 device
最初的问题是 编译内核添加了 spi 支持，配置了 board 后，加载25q64驱动不执行probe 函数。
然后发现是，spi-s3c24xx.c 中的 probe 没有执行完就退出了 没有生成 spi-master
/drivers/spi/spi-s3c24xx.c
定位在 出错
hw->clk = devm_clk_get(&pdev->dev, "spi");
if (IS_ERR(hw->clk)) {
dev_err(&pdev->dev, "No clock for device\n");
err = PTR_ERR(hw->clk);
goto err_no_pdata;
}
对应下面
struct clk *clk_get(struct device *dev, const char *con_id)
{
const char *dev_id = dev ? dev_name(dev) : NULL;
struct clk *clk;
if (dev) {
clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id);
if (!IS_ERR(clk) || PTR_ERR(clk) == -EPROBE_DEFER)
return clk;
}
return clk_get_sys(dev_id, con_id);
}
看一下 clk_get_sys(dev_id, con_id) 实现
struct clk *clk_get_sys(const char *dev_id, const char *con_id)
{
struct clk_lookup *cl;
struct clk *clk = NULL;
mutex_lock(&clocks_mutex);
cl = clk_find(dev_id, con_id);
if (!cl)
goto out;
clk = __clk_create_clk(__clk_get_hw(cl->clk), dev_id, con_id);
if (IS_ERR(clk))
goto out;
if (!__clk_get(clk)) {
__clk_free_clk(clk);
cl = NULL;
goto out;
}
out:
mutex_unlock(&clocks_mutex);
return cl ? clk : ERR_PTR(-ENOENT);
}
查找 clk_find(dev_id, con_id); 函数
static struct clk_lookup *clk_find(const char *dev_id, const char *con_id)
{
struct clk_lookup *p, *cl = NULL;
int match, best_found = 0, best_possible = 0;
if (dev_id)
best_possible += 2;
if (con_id)
best_possible += 1;
list_for_each_entry(p, &clocks, node) {
match = 0;
if (p->dev_id) {
if (!dev_id || strcmp(p->dev_id, dev_id))
continue;
match += 2;
}
if (p->con_id) {
if (!con_id || strcmp(p->con_id, con_id))
continue;
match += 1;
}
if (match > best_found) {
cl = p;
if (match != best_possible)
best_found = match;
else
break;
}
}
return cl;
}
检查 clocks 创建过程，有非常多的嵌套，就像是 俄罗期套娃。
/arch/arm/mach-s3c24xx/mach-smdk2440.c
smdk2440_init_time()
/arch/arm/mach-s3c24xx/common.c
s3c2440_init_clocks(12000000)
/drivers/clk/samsung/clk-s3c2410.c
s3c2410_common_clk_init(NULL, 12000000, 1, S3C24XX_VA_CLKPWR);
/* Register common internal clocks. 通用的内部时钟 */
samsung_clk_register_mux(ctx, s3c2410_common_muxes,
ARRAY_SIZE(s3c2410_common_muxes));
samsung_clk_register_div(ctx, s3c2410_common_dividers,
ARRAY_SIZE(s3c2410_common_dividers));
samsung_clk_register_gate(ctx, s3c2410_common_gates,
ARRAY_SIZE(s3c2410_common_gates));
if (current_soc == S3C2440 || current_soc == S3C2442) {
samsung_clk_register_div(ctx, s3c244x_common_dividers,
ARRAY_SIZE(s3c244x_common_dividers));
samsung_clk_register_gate(ctx, s3c244x_common_gates,
ARRAY_SIZE(s3c244x_common_gates));
samsung_clk_register_mux(ctx, s3c244x_common_muxes,
ARRAY_SIZE(s3c244x_common_muxes));
samsung_clk_register_fixed_factor(ctx, s3c244x_common_ffactor,
ARRAY_SIZE(s3c244x_common_ffactor));
}
/* 注册别名
* Register common aliases at the end, as some of the aliased clocks
* are SoC specific.
*/
samsung_clk_register_alias(ctx, s3c2410_common_aliases,
ARRAY_SIZE(s3c2410_common_aliases));
if (current_soc == S3C2440 || current_soc == S3C2442) {
samsung_clk_register_alias(ctx, s3c244x_common_aliases,
ARRAY_SIZE(s3c244x_common_aliases));
}
最终定位到
struct samsung_gate_clock s3c2410_common_gates[] __initdata = http://www.mamicode.com/{
GATE(PCLK_SPI, "spi", "pclk", CLKCON, 18, 0, 0),
GATE(PCLK_I2S, "i2s", "pclk", CLKCON, 17, 0, 0),
GATE(PCLK_I2C, "i2c", "pclk", CLKCON, 16, 0, 0),
GATE(PCLK_ADC, "adc", "pclk", CLKCON, 15, 0, 0),
GATE(PCLK_RTC, "rtc", "pclk", CLKCON, 14, 0, 0),
GATE(PCLK_GPIO, "gpio", "pclk", CLKCON, 13, CLK_IGNORE_UNUSED, 0),
GATE(PCLK_UART2, "uart2", "pclk", CLKCON, 12, 0, 0),
GATE(PCLK_UART1, "uart1", "pclk", CLKCON, 11, 0, 0),
GATE(PCLK_UART0, "uart0", "pclk", CLKCON, 10, 0, 0),
GATE(PCLK_SDI, "sdi", "pclk", CLKCON, 9, 0, 0),
GATE(PCLK_PWM, "pwm", "pclk", CLKCON, 8, 0, 0),
GATE(HCLK_USBD, "usb-device", "hclk", CLKCON, 7, 0, 0),
GATE(HCLK_USBH, "usb-host", "hclk", CLKCON, 6, 0, 0),
GATE(HCLK_LCD, "lcd", "hclk", CLKCON, 5, 0, 0),
GATE(HCLK_NAND, "nand", "hclk", CLKCON, 4, 0, 0),
};
/* should be added _after_ the soc-specific clocks are created */
struct samsung_clock_alias s3c2410_common_aliases[] __initdata = http://www.mamicode.com/{
ALIAS(PCLK_I2C, "s3c2410-i2c.0", "i2c"),
ALIAS(PCLK_ADC, NULL, "adc"),
ALIAS(PCLK_RTC, NULL, "rtc"),
ALIAS(PCLK_PWM, NULL, "timers"),
ALIAS(HCLK_LCD, NULL, "lcd"),
ALIAS(HCLK_USBD, NULL, "usb-device"),
ALIAS(HCLK_USBH, NULL, "usb-host"),
ALIAS(UCLK, NULL, "usb-bus-host"),
ALIAS(UCLK, NULL, "usb-bus-gadget"),
ALIAS(ARMCLK, NULL, "armclk"),
ALIAS(UCLK, NULL, "uclk"),
ALIAS(HCLK, NULL, "hclk"),
ALIAS(MPLL, NULL, "mpll"),
ALIAS(FCLK, NULL, "fclk"),
ALIAS(PCLK, NULL, "watchdog"),
ALIAS(PCLK_SDI, NULL, "sdi"),
ALIAS(HCLK_NAND, NULL, "nand"),
ALIAS(PCLK_I2S, NULL, "iis"),
ALIAS(PCLK_I2C, NULL, "i2c"),
ALIAS(PCLK_SPI, NULL, "spi"), // 添加一行
};
使用新内核启动
WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:1067 clk_core_enable+0x94/0xa4()
Modules linked in:
不确定到底是何原因引起是 SPI 时钟添加的方式不对，还是spi-s3c24xx.c 中使用的不对。
先改为 i2c 启动看是否还有错误
hw->clk = devm_clk_get(&pdev->dev, "i2c");
这一次启动没有了 WARNING 信息，说明 spi-s3c24xx.c 驱动没有问题。
后来我又一想，可能 是因为内核中有 I2C 的驱动，I2C 初始化了时钟，所以 没有问题。
重新编译 内核去掉了 I2C 后，重新启动，果然还是有 WARNING 说明 spi-s3c24xx.c 有问题。
自己写一个小的驱动来测试下 SPI 时钟是否可以工作使用。
程序还不是很好用，但是可以读到 flash id ，id 好像也不太对。 后期在更新。
1 #include <linux/err.h> 2 #include <linux/kernel.h> 3 #include <linux/module.h> 4 #include <linux/slab.h> 5 #include <linux/delay.h> 6 #include <linux/io.h> 7 #include <linux/clk.h> 8 9 10 static volatile unsigned long *gpg_con; 11 static volatile unsigned long *gpg_dat; 12 13 /** 14 * 引脚定义 15 * SPIMI GPG5 SPICLK GPG7 16 * SPIMO GPG6 nSSSPI GPG2 17 */ 18 19 struct spi_regs { 20 unsigned long spcon; //0x59000000 21 unsigned long spsta; //0x59000004 22 unsigned long sppin; //0x59000008 23 unsigned long sppre; //0x5900000c 24 unsigned long sptdat; //0x59000010 25 unsigned long sprdat; //0x59000014 26 }; 27 28 static volatile struct spi_regs *spi_reg; 29 static void spi_set_cs(int enable){ 30 //低电平选中 31 if(enable) 32 { 33 *gpg_dat &= ~(1<<2); 34 } 35 else 36 { 37 *gpg_dat |= 1<<2; 38 } 39 } 40 41 static void spi_ready(void) 42 { 43 while(! (spi_reg->spsta & 1)); 44 } 45 46 static unsigned char spi_read_byte(void) 47 { 48 unsigned char val = 0; 49 spi_reg->sptdat = 0xff; 50 spi_ready(); 51 val = spi_reg->sprdat & 0xff; 52 return val; 53 } 54 55 static void spi_init(void) 56 { 57 struct clk *clk; 58 clk = clk_get(NULL, "spi"); 59 if (IS_ERR(clk)) 60 { 61 printk("get spi clock error \n"); 62 return ; 63 } 64 clk_prepare_enable(clk); 65 usleep_range(1000, 1100); 66 //清0 67 *gpg_con &= ~(3<<(2*2)) | (3<<(5*2)) | (3<<(6*2)) | (3<<(7*2)); 68 //设为SPI功能 69 *gpg_con |= (1<<(2*2)) | (3<<(5*2)) | (3<<(6*2)) | (3<<(7*2)); 70 *gpg_dat |= 1<<2; 71 //启用 SCK 72 //主机模式 73 spi_reg->spcon = (1<<4) | (1<<3); 74 spi_reg->sppre = 2; 75 } 76 77 static void spi_write_byte(unsigned char val) 78 { 79 spi_ready(); 80 spi_reg->sptdat = val; 81 } 82 83 static void w25q_write_addr(unsigned int addr) 84 { 85 spi_write_byte((addr >> 16) & 0xff); 86 spi_write_byte((addr >> 8) & 0xff); 87 spi_write_byte(addr & 0xff); 88 } 89 90 static void w25q_init(void) 91 { 92 spi_init(); 93 } 94 95 static void w25q_read_id(unsigned char *factory_id, unsigned char *dev_id) 96 { 97 *factory_id = 0; 98 *dev_id = 0; 99 spi_set_cs(1); 100 spi_write_byte(0x90); 101 w25q_write_addr(0x0); 102 *factory_id = spi_read_byte(); 103 *dev_id = spi_read_byte(); 104 spi_set_cs(0); 105 } 106 107 static int spi_25q_init(void) 108 { 109 unsigned char factory_id=0, dev_id=0; 110 111 gpg_con = ioremap(0x56000060, 8); 112 gpg_dat = gpg_con+1; 113 114 spi_reg = ioremap(0x59000020, sizeof(struct spi_regs)); 115 //初始化 116 w25q_init(); 117 118 //读ID 119 w25q_read_id(&factory_id, &dev_id); 120 printk("w25q64 fid: 0x%2x devid: 0x%2x \n", factory_id, dev_id); 121 122 123 return 0; 124 } 125 126 static void spi_25q_exit(void) 127 { 128 iounmap(gpg_con); 129 iounmap(spi_reg); 130 } 131 module_init(spi_25q_init); 132 module_exit(spi_25q_exit); 133 MODULE_LICENSE("GPL");
linux4.1.36 SPI 时钟找不到 不生成设备 device