二、设备和驱动的注册时序
一、引言
在platform驱动程序框架中，我们了解到，platform设备和驱动最终会挂载在platform总线上，platform总线会对设备和驱动进行匹配。那么设备和驱动是怎么注册到platform框架中去的，其先后顺序又是怎样的？
二、设备和驱动注册
platform_device_register注册设备
![]()
1 /**
2 * platform_device_register - add a platform-level device
3 * @pdev: platform device we're adding
4 */
5 int platform_device_register(
struct platform_device *
pdev)
6 {
7 device_initialize(&pdev->
dev);
8 return platform_device_add(pdev);
9 }
10 EXPORT_SYMBOL_GPL(platform_device_register);
platform_device_register
platform_driver_register注册驱动
![]()
1 /**
2 * platform_driver_register
3 * @drv: platform driver structure
4 */
5 int platform_driver_register(
struct platform_driver *
drv)
6 {
7 drv->driver.bus = &
platform_bus_type;
8 if (drv->
probe)
9 drv->driver.probe =
platform_drv_probe;
10 if (drv->
remove)
11 drv->driver.remove =
platform_drv_remove;
12 if (drv->
shutdown)
13 drv->driver.shutdown =
platform_drv_shutdown;
14
15 return driver_register(&drv->
driver);
16 }
17 EXPORT_SYMBOL_GPL(platform_driver_register);
platform_driver_register
设备注册sample
![]()
1 static struct plat_serial8250_port serial_platform_data[] =
{
2 {
3 .membase =
OMAP1_IO_ADDRESS(OMAP_UART1_BASE),
4 .mapbase =
OMAP_UART1_BASE,
5 .irq =
INT_UART1,
6 .flags =
UPF_BOOT_AUTOCONF,
7 .iotype =
UPIO_MEM,
8 .regshift =
2,
9 .uartclk = OMAP16XX_BASE_BAUD *
16,
10 },
11 {
12 .membase =
OMAP1_IO_ADDRESS(OMAP_UART2_BASE),
13 .mapbase =
OMAP_UART2_BASE,
14 .irq =
INT_UART2,
15 .flags =
UPF_BOOT_AUTOCONF,
16 .iotype =
UPIO_MEM,
17 .regshift =
2,
18 .uartclk = OMAP16XX_BASE_BAUD *
16,
19 },
20 {
21 .membase =
OMAP1_IO_ADDRESS(OMAP_UART3_BASE),
22 .mapbase =
OMAP_UART3_BASE,
23 .irq =
INT_UART3,
24 .flags =
UPF_BOOT_AUTOCONF,
25 .iotype =
UPIO_MEM,
26 .regshift =
2,
27 .uartclk = OMAP16XX_BASE_BAUD *
16,
28 },
29 { },
30 };
31
32 static struct platform_device serial_device =
{
33 .name =
"serial8250",
34 .id =
PLAT8250_DEV_PLATFORM,
35 .dev =
{
36 .platform_data =
serial_platform_data,
37 },
38 };
39
40 static int __init omap_init(
void)
41 {
42 return platform_device_register(&
serial_device);
43 }
44 arch_initcall(omap_init);
device register sample
驱动注册sample
![]()
1 static int __init serial_txx9_init(
void)
2 {
3 int ret;
4
5 printk(KERN_INFO
"%s version %s\n", serial_name, serial_version);
6
7 ret = uart_register_driver(&
serial_txx9_reg);
8 if (ret)
9 goto out;
10
11 serial_txx9_plat_devs = platform_device_alloc(
"serial_txx9", -
1);
12 if (!
serial_txx9_plat_devs) {
13 ret = -
ENOMEM;
14 goto unreg_uart_drv;
15 }
16
17 ret =
platform_device_add(serial_txx9_plat_devs);
18 if (ret)
19 goto put_dev;
20
21 serial_txx9_register_ports(&
serial_txx9_reg,
22 &serial_txx9_plat_devs->
dev);
23
24 ret = platform_driver_register(&
serial_txx9_plat_driver);
25 if (ret)
26 goto del_dev;
27
28 #ifdef ENABLE_SERIAL_TXX9_PCI
29 ret = pci_register_driver(&
serial_txx9_pci_driver);
30 #endif
31 if (ret ==
0)
32 goto out;
33
34 del_dev:
35 platform_device_del(serial_txx9_plat_devs);
36 put_dev:
37 platform_device_put(serial_txx9_plat_devs);
38 unreg_uart_drv:
39 uart_unregister_driver(&
serial_txx9_reg);
40 out:
41 return ret;
42 }
43
44 module_init(serial_txx9_init);
driver register sample
设备注册时定义了该设备用到的一些硬件资源，如中断线，内存地址范围，稳压电源等。
驱动注册时定义了probe、remove等函数，在probe阶段，会做一些初始化动作，如将中断处理函数关联到设备的中断线上。
由此看来，先注册设备再注册驱动。
三、init函数调用时序
device初始化用到了宏arch_initcall，driver初始化用到了宏module_init。
在include\linux\init.h中定义了arch_initcall,其根据level标示，在load阶段会按顺序加载。
![]()
1 /* initcalls are now grouped by functionality into separate
2 * subsections. Ordering inside the subsections is determined
3 * by link order.
4 * For backwards compatibility, initcall() puts the call in
5 * the device init subsection.
6 *
7 * The `id' arg to __define_initcall() is needed so that multiple initcalls
8 * can point at the same handler without causing duplicate-symbol build errors.
9 */
10
11 #define __define_initcall(level,fn,id) \
12 static initcall_t __initcall_##fn##id __used \
13 __attribute__((__section__(
".initcall" level
".init"))) = fn
__define_initcall
arch_initcall的调用顺序是3。
![]()
1 #define core_initcall(fn) __define_initcall("1",fn,1)
2 #define core_initcall_sync(fn) __define_initcall("1s",fn,1s)
3 #define postcore_initcall(fn) __define_initcall("2",fn,2)
4 #define postcore_initcall_sync(fn) __define_initcall("2s",fn,2s)
5 #define arch_initcall(fn) __define_initcall("3",fn,3)
6 #define arch_initcall_sync(fn) __define_initcall("3s",fn,3s)
7 #define subsys_initcall(fn) __define_initcall("4",fn,4)
8 #define subsys_initcall_sync(fn) __define_initcall("4s",fn,4s)
9 #define fs_initcall(fn) __define_initcall("5",fn,5)
10 #define fs_initcall_sync(fn) __define_initcall("5s",fn,5s)
11 #define rootfs_initcall(fn) __define_initcall("rootfs",fn,rootfs)
12 #define device_initcall(fn) __define_initcall("6",fn,6)
13 #define device_initcall_sync(fn) __define_initcall("6s",fn,6s)
14 #define late_initcall(fn) __define_initcall("7",fn,7)
15 #define late_initcall_sync(fn) __define_initcall("7s",fn,7s)
arch_initcall
arch_initcall和module_init宏最终都会扩展成__define_initcall，将函数装载到__initcall段中，其根据level在此段中排序。
vmlinux的load脚本，其中有initcall段定义。
![]()
1 /* ld script to make ARM Linux kernel
2 * taken from the i386 version by Russell King
3 * Written by Martin Mares <mj@atrey.karlin.mff.cuni.cz>
4 */
5
6 #include <asm-generic/vmlinux.lds.h>
7 #include <asm/thread_info.h>
8 #include <asm/memory.h>
9 #include <asm/page.h>
10
11 OUTPUT_ARCH(arm)
12 ENTRY(stext)
13
14 #ifndef __ARMEB__
15 jiffies =
jiffies_64;
16 #else
17 jiffies = jiffies_64 +
4;
18 #endif
19
20 SECTIONS
21 {
22 #ifdef CONFIG_XIP_KERNEL
23 . =
XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR);
24 #else
25 . = PAGE_OFFSET +
TEXT_OFFSET;
26 #endif
27 .text.head : {
28 _stext =
.;
29 _sinittext =
.;
30 *
(.text.head)
31 }
32
33 .init : {
/* Init code and data */
34 INIT_TEXT
35 _einittext =
.;
36 __proc_info_begin =
.;
37 *
(.proc.info.init)
38 __proc_info_end =
.;
39 __arch_info_begin =
.;
40 *
(.arch.info.init)
41 __arch_info_end =
.;
42 __tagtable_begin =
.;
43 *
(.taglist.init)
44 __tagtable_end =
.;
45 . = ALIGN(
16);
46 __setup_start =
.;
47 *
(.init.setup)
48 __setup_end =
.;
49 __early_begin =
.;
50 *
(.early_param.init)
51 __early_end =
.;
52 __initcall_start =
.;
53 INITCALLS
54 __initcall_end =
.;
55 __con_initcall_start =
.;
56 *
(.con_initcall.init)
57 __con_initcall_end =
.;
58 __security_initcall_start =
.;
59 *
(.security_initcall.init)
60 __security_initcall_end =
.;
61 #ifdef CONFIG_BLK_DEV_INITRD
62 . = ALIGN(
32);
63 __initramfs_start =
.;
64 usr/built-
in.o(.init.ramfs)
65 __initramfs_end =
.;
66 #endif
67 . =
ALIGN(PAGE_SIZE);
68 __per_cpu_load =
.;
69 __per_cpu_start =
.;
70 *
(.data.percpu.page_aligned)
71 *
(.data.percpu)
72 *
(.data.percpu.shared_aligned)
73 __per_cpu_end =
.;
74 #ifndef CONFIG_XIP_KERNEL
75 __init_begin =
_stext;
76 INIT_DATA
77 . =
ALIGN(PAGE_SIZE);
78 __init_end =
.;
79 #endif
80 }
81
82 /DISCARD/ : {
/* Exit code and data */
83 EXIT_TEXT
84 EXIT_DATA
85 *
(.exitcall.exit)
86 *
(.discard)
87 *
(.ARM.exidx.exit.text)
88 *
(.ARM.extab.exit.text)
89 #ifndef CONFIG_HOTPLUG_CPU
90 *
(.ARM.exidx.cpuexit.text)
91 *
(.ARM.extab.cpuexit.text)
92 #endif
93 #ifndef CONFIG_HOTPLUG
94 *
(.ARM.exidx.devexit.text)
95 *
(.ARM.extab.devexit.text)
96 #endif
97 #ifndef CONFIG_MMU
98 *
(.fixup)
99 *
(__ex_table)
100 #endif
101 }
102
103 .text : {
/* Real text segment */
104 _text = .;
/* Text and read-only data */
105 __exception_text_start =
.;
106 *
(.exception.text)
107 __exception_text_end =
.;
108 TEXT_TEXT
109 SCHED_TEXT
110 LOCK_TEXT
111 KPROBES_TEXT
112 #ifdef CONFIG_MMU
113 *
(.fixup)
114 #endif
115 *
(.gnu.warning)
116 *
(.rodata)
117 *(.rodata.*
)
118 *
(.glue_7)
119 *
(.glue_7t)
120 *(.got)
/* Global offset table */
121 }
122
123 RO_DATA(PAGE_SIZE)
124
125 _etext = .;
/* End of text and rodata section */
126
127 #ifdef CONFIG_ARM_UNWIND
128 /*
129 * Stack unwinding tables
130 */
131 . = ALIGN(
8);
132 .ARM.unwind_idx : {
133 __start_unwind_idx =
.;
134 *(.ARM.exidx*
)
135 __stop_unwind_idx =
.;
136 }
137 .ARM.unwind_tab : {
138 __start_unwind_tab =
.;
139 *(.ARM.extab*
)
140 __stop_unwind_tab =
.;
141 }
142 #endif
143
144 #ifdef CONFIG_XIP_KERNEL
145 __data_loc = ALIGN(
4);
/* location in binary */
146 . = PAGE_OFFSET +
TEXT_OFFSET;
147 #else
148 . =
ALIGN(THREAD_SIZE);
149 __data_loc =
.;
150 #endif
151
152 .data : AT(__data_loc) {
153 _data = .;
/* address in memory */
154 _sdata =
.;
155
156 /*
157 * first, the init task union, aligned
158 * to an 8192 byte boundary.
159 */
160 *
(.data.init_task)
161
162 #ifdef CONFIG_XIP_KERNEL
163 . =
ALIGN(PAGE_SIZE);
164 __init_begin =
.;
165 INIT_DATA
166 . =
ALIGN(PAGE_SIZE);
167 __init_end =
.;
168 #endif
169
170 . =
ALIGN(PAGE_SIZE);
171 __nosave_begin =
.;
172 *
(.data.nosave)
173 . =
ALIGN(PAGE_SIZE);
174 __nosave_end =
.;
175
176 /*
177 * then the cacheline aligned data
178 */
179 . = ALIGN(
32);
180 *
(.data.cacheline_aligned)
181
182 /*
183 * The exception fixup table (might need resorting at runtime)
184 */
185 . = ALIGN(
32);
186 __start___ex_table =
.;
187 #ifdef CONFIG_MMU
188 *
(__ex_table)
189 #endif
190 __stop___ex_table =
.;
191
192 /*
193 * and the usual data section
194 */
195 DATA_DATA
196 CONSTRUCTORS
197
198 _edata =
.;
199 }
200 _edata_loc = __data_loc +
SIZEOF(.data);
201
202 #ifdef CONFIG_HAVE_TCM
203 /*
204 * We align everything to a page boundary so we can
205 * free it after init has commenced and TCM contents have
206 * been copied to its destination.
207 */
208 .tcm_start : {
209 . =
ALIGN(PAGE_SIZE);
210 __tcm_start =
.;
211 __itcm_start =
.;
212 }
213
214 /*
215 * Link these to the ITCM RAM
216 * Put VMA to the TCM address and LMA to the common RAM
217 * and we'll upload the contents from RAM to TCM and free
218 * the used RAM after that.
219 */
220 .text_itcm ITCM_OFFSET : AT(__itcm_start)
221 {
222 __sitcm_text =
.;
223 *
(.tcm.text)
224 *
(.tcm.rodata)
225 . = ALIGN(
4);
226 __eitcm_text =
.;
227 }
228
229 /*
230 * Reset the dot pointer, this is needed to create the
231 * relative __dtcm_start below (to be used as extern in code).
232 */
233 . = ADDR(.tcm_start) + SIZEOF(.tcm_start) +
SIZEOF(.text_itcm);
234
235 .dtcm_start : {
236 __dtcm_start =
.;
237 }
238
239 /* TODO: add remainder of ITCM as well, that can be used for data! */
240 .data_dtcm DTCM_OFFSET : AT(__dtcm_start)
241 {
242 . = ALIGN(
4);
243 __sdtcm_data =
.;
244 *
(.tcm.data)
245 . = ALIGN(
4);
246 __edtcm_data =
.;
247 }
248
249 /* Reset the dot pointer or the linker gets confused */
250 . = ADDR(.dtcm_start) +
SIZEOF(.data_dtcm);
251
252 /* End marker for freeing TCM copy in linked object */
253 .tcm_end : AT(ADDR(.dtcm_start) +
SIZEOF(.data_dtcm)){
254 . =
ALIGN(PAGE_SIZE);
255 __tcm_end =
.;
256 }
257 #endif
258
259 .bss : {
260 __bss_start = .;
/* BSS */
261 *
(.bss)
262 *
(COMMON)
263 __bss_stop =
.;
264 _end =
.;
265 }
266 /* Stabs debugging sections. */
267 .stab
0 : { *
(.stab) }
268 .stabstr
0 : { *
(.stabstr) }
269 .stab.excl
0 : { *
(.stab.excl) }
270 .stab.exclstr
0 : { *
(.stab.exclstr) }
271 .stab.index
0 : { *
(.stab.index) }
272 .stab.indexstr
0 : { *
(.stab.indexstr) }
273 .comment
0 : { *
(.comment) }
274 }
275
276 /*
277 * These must never be empty
278 * If you have to comment these two assert statements out, your
279 * binutils is too old (for other reasons as well)
280 */
281 ASSERT((__proc_info_end - __proc_info_begin),
"missing CPU support")
282 ASSERT((__arch_info_end - __arch_info_begin),
"no machine record defined")
vmlinux.lds
在do_initcalls中会从initcall段的函数地址开始，依次调用此段中的函数，设备和驱动的初始化即在此被调用。
调用顺序：
start_kernel->reset_init->kernel_init->do_basic_setup->do_initcalls
![]()
1 extern initcall_t __initcall_start[], __initcall_end[], __early_initcall_end[];
2
3 static void __init do_initcalls(
void)
4 {
5 initcall_t *
call;
6
7 for (call = __early_initcall_end; call < __initcall_end; call++
)
8 do_one_initcall(*
call);
9
10 /* Make sure there is no pending stuff from the initcall sequence */
11 flush_scheduled_work();
12 }
do_initcalls
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