diff options
| -rw-r--r-- | Documentation/driver-model/platform.txt | 59 | ||||
| -rw-r--r-- | drivers/base/platform.c | 239 | ||||
| -rw-r--r-- | include/linux/init.h | 1 | ||||
| -rw-r--r-- | include/linux/platform_device.h | 42 | ||||
| -rw-r--r-- | init/main.c | 7 |
5 files changed, 347 insertions, 1 deletions
diff --git a/Documentation/driver-model/platform.txt b/Documentation/driver-model/platform.txt index 83009fdcbbc8..2e2c2ea90ceb 100644 --- a/Documentation/driver-model/platform.txt +++ b/Documentation/driver-model/platform.txt @@ -169,3 +169,62 @@ three different ways to find such a match: be probed later if another device registers. (Which is OK, since this interface is only for use with non-hotpluggable devices.) + +Early Platform Devices and Drivers +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The early platform interfaces provide platform data to platform device +drivers early on during the system boot. The code is built on top of the +early_param() command line parsing and can be executed very early on. + +Example: "earlyprintk" class early serial console in 6 steps + +1. Registering early platform device data +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The architecture code registers platform device data using the function +early_platform_add_devices(). In the case of early serial console this +should be hardware configuration for the serial port. Devices registered +at this point will later on be matched against early platform drivers. + +2. Parsing kernel command line +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The architecture code calls parse_early_param() to parse the kernel +command line. This will execute all matching early_param() callbacks. +User specified early platform devices will be registered at this point. +For the early serial console case the user can specify port on the +kernel command line as "earlyprintk=serial.0" where "earlyprintk" is +the class string, "serial" is the name of the platfrom driver and +0 is the platform device id. If the id is -1 then the dot and the +id can be omitted. + +3. Installing early platform drivers belonging to a certain class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The architecture code may optionally force registration of all early +platform drivers belonging to a certain class using the function +early_platform_driver_register_all(). User specified devices from +step 2 have priority over these. This step is omitted by the serial +driver example since the early serial driver code should be disabled +unless the user has specified port on the kernel command line. + +4. Early platform driver registration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Compiled-in platform drivers making use of early_platform_init() are +automatically registered during step 2 or 3. The serial driver example +should use early_platform_init("earlyprintk", &platform_driver). + +5. Probing of early platform drivers belonging to a certain class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The architecture code calls early_platform_driver_probe() to match +registered early platform devices associated with a certain class with +registered early platform drivers. Matched devices will get probed(). +This step can be executed at any point during the early boot. As soon +as possible may be good for the serial port case. + +6. Inside the early platform driver probe() +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The driver code needs to take special care during early boot, especially +when it comes to memory allocation and interrupt registration. The code +in the probe() function can use is_early_platform_device() to check if +it is called at early platform device or at the regular platform device +time. The early serial driver performs register_console() at this point. + +For further information, see <linux/platform_device.h>. diff --git a/drivers/base/platform.c b/drivers/base/platform.c index d2198f64ad4e..b5b6c973a2e0 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -990,6 +990,8 @@ int __init platform_bus_init(void) { int error; + early_platform_cleanup(); + error = device_register(&platform_bus); if (error) return error; @@ -1020,3 +1022,240 @@ u64 dma_get_required_mask(struct device *dev) } EXPORT_SYMBOL_GPL(dma_get_required_mask); #endif + +static __initdata LIST_HEAD(early_platform_driver_list); +static __initdata LIST_HEAD(early_platform_device_list); + +/** + * early_platform_driver_register + * @edrv: early_platform driver structure + * @buf: string passed from early_param() + */ +int __init early_platform_driver_register(struct early_platform_driver *epdrv, + char *buf) +{ + unsigned long index; + int n; + + /* Simply add the driver to the end of the global list. + * Drivers will by default be put on the list in compiled-in order. + */ + if (!epdrv->list.next) { + INIT_LIST_HEAD(&epdrv->list); + list_add_tail(&epdrv->list, &early_platform_driver_list); + } + + /* If the user has specified device then make sure the driver + * gets prioritized. The driver of the last device specified on + * command line will be put first on the list. + */ + n = strlen(epdrv->pdrv->driver.name); + if (buf && !strncmp(buf, epdrv->pdrv->driver.name, n)) { + list_move(&epdrv->list, &early_platform_driver_list); + + if (!strcmp(buf, epdrv->pdrv->driver.name)) + epdrv->requested_id = -1; + else if (buf[n] == '.' && strict_strtoul(&buf[n + 1], 10, + &index) == 0) + epdrv->requested_id = index; + else + epdrv->requested_id = EARLY_PLATFORM_ID_ERROR; + } + + return 0; +} + +/** + * early_platform_add_devices - add a numbers of early platform devices + * @devs: array of early platform devices to add + * @num: number of early platform devices in array + */ +void __init early_platform_add_devices(struct platform_device **devs, int num) +{ + struct device *dev; + int i; + + /* simply add the devices to list */ + for (i = 0; i < num; i++) { + dev = &devs[i]->dev; + + if (!dev->devres_head.next) { + INIT_LIST_HEAD(&dev->devres_head); + list_add_tail(&dev->devres_head, + &early_platform_device_list); + } + } +} + +/** + * early_platform_driver_register_all + * @class_str: string to identify early platform driver class + */ +void __init early_platform_driver_register_all(char *class_str) +{ + /* The "class_str" parameter may or may not be present on the kernel + * command line. If it is present then there may be more than one + * matching parameter. + * + * Since we register our early platform drivers using early_param() + * we need to make sure that they also get registered in the case + * when the parameter is missing from the kernel command line. + * + * We use parse_early_options() to make sure the early_param() gets + * called at least once. The early_param() may be called more than + * once since the name of the preferred device may be specified on + * the kernel command line. early_platform_driver_register() handles + * this case for us. + */ + parse_early_options(class_str); +} + +/** + * early_platform_match + * @edrv: early platform driver structure + * @id: id to match against + */ +static __init struct platform_device * +early_platform_match(struct early_platform_driver *epdrv, int id) +{ + struct platform_device *pd; + + list_for_each_entry(pd, &early_platform_device_list, dev.devres_head) + if (platform_match(&pd->dev, &epdrv->pdrv->driver)) + if (pd->id == id) + return pd; + + return NULL; +} + +/** + * early_platform_left + * @edrv: early platform driver structure + * @id: return true if id or above exists + */ +static __init int early_platform_left(struct early_platform_driver *epdrv, + int id) +{ + struct platform_device *pd; + + list_for_each_entry(pd, &early_platform_device_list, dev.devres_head) + if (platform_match(&pd->dev, &epdrv->pdrv->driver)) + if (pd->id >= id) + return 1; + + return 0; +} + +/** + * early_platform_driver_probe_id + * @class_str: string to identify early platform driver class + * @id: id to match against + * @nr_probe: number of platform devices to successfully probe before exiting + */ +static int __init early_platform_driver_probe_id(char *class_str, + int id, + int nr_probe) +{ + struct early_platform_driver *epdrv; + struct platform_device *match; + int match_id; + int n = 0; + int left = 0; + + list_for_each_entry(epdrv, &early_platform_driver_list, list) { + /* only use drivers matching our class_str */ + if (strcmp(class_str, epdrv->class_str)) + continue; + + if (id == -2) { + match_id = epdrv->requested_id; + left = 1; + + } else { + match_id = id; + left += early_platform_left(epdrv, id); + + /* skip requested id */ + switch (epdrv->requested_id) { + case EARLY_PLATFORM_ID_ERROR: + case EARLY_PLATFORM_ID_UNSET: + break; + default: + if (epdrv->requested_id == id) + match_id = EARLY_PLATFORM_ID_UNSET; + } + } + + switch (match_id) { + case EARLY_PLATFORM_ID_ERROR: + pr_warning("%s: unable to parse %s parameter\n", + class_str, epdrv->pdrv->driver.name); + /* fall-through */ + case EARLY_PLATFORM_ID_UNSET: + match = NULL; + break; + default: + match = early_platform_match(epdrv, match_id); + } + + if (match) { + if (epdrv->pdrv->probe(match)) + pr_warning("%s: unable to probe %s early.\n", + class_str, match->name); + else + n++; + } + + if (n >= nr_probe) + break; + } + + if (left) + return n; + else + return -ENODEV; +} + +/** + * early_platform_driver_probe + * @class_str: string to identify early platform driver class + * @nr_probe: number of platform devices to successfully probe before exiting + * @user_only: only probe user specified early platform devices + */ +int __init early_platform_driver_probe(char *class_str, + int nr_probe, + int user_only) +{ + int k, n, i; + + n = 0; + for (i = -2; n < nr_probe; i++) { + k = early_platform_driver_probe_id(class_str, i, nr_probe - n); + + if (k < 0) + break; + + n += k; + + if (user_only) + break; + } + + return n; +} + +/** + * early_platform_cleanup - clean up early platform code + */ +void __init early_platform_cleanup(void) +{ + struct platform_device *pd, *pd2; + + /* clean up the devres list used to chain devices */ + list_for_each_entry_safe(pd, pd2, &early_platform_device_list, + dev.devres_head) { + list_del(&pd->dev.devres_head); + memset(&pd->dev.devres_head, 0, sizeof(pd->dev.devres_head)); + } +} + diff --git a/include/linux/init.h b/include/linux/init.h index 68cb0265d009..f121a7a10c3d 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -247,6 +247,7 @@ struct obs_kernel_param { /* Relies on boot_command_line being set */ void __init parse_early_param(void); +void __init parse_early_options(char *cmdline); #endif /* __ASSEMBLY__ */ /** diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index 76e470a299bf..72736fd8223c 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -77,4 +77,46 @@ extern int platform_driver_probe(struct platform_driver *driver, #define platform_get_drvdata(_dev) dev_get_drvdata(&(_dev)->dev) #define platform_set_drvdata(_dev,data) dev_set_drvdata(&(_dev)->dev, (data)) +/* early platform driver interface */ +struct early_platform_driver { + const char *class_str; + struct platform_driver *pdrv; + struct list_head list; + int requested_id; +}; + +#define EARLY_PLATFORM_ID_UNSET -2 +#define EARLY_PLATFORM_ID_ERROR -3 + +extern int early_platform_driver_register(struct early_platform_driver *epdrv, + char *buf); +extern void early_platform_add_devices(struct platform_device **devs, int num); + +static inline int is_early_platform_device(struct platform_device *pdev) +{ + return !pdev->dev.driver; +} + +extern void early_platform_driver_register_all(char *class_str); +extern int early_platform_driver_probe(char *class_str, + int nr_probe, int user_only); +extern void early_platform_cleanup(void); + + +#ifndef MODULE +#define early_platform_init(class_string, platform_driver) \ +static __initdata struct early_platform_driver early_driver = { \ + .class_str = class_string, \ + .pdrv = platform_driver, \ + .requested_id = EARLY_PLATFORM_ID_UNSET, \ +}; \ +static int __init early_platform_driver_setup_func(char *buf) \ +{ \ + return early_platform_driver_register(&early_driver, buf); \ +} \ +early_param(class_string, early_platform_driver_setup_func) +#else /* MODULE */ +#define early_platform_init(class_string, platform_driver) +#endif /* MODULE */ + #endif /* _PLATFORM_DEVICE_H_ */ diff --git a/init/main.c b/init/main.c index 3585f073d636..3bbf93be744c 100644 --- a/init/main.c +++ b/init/main.c @@ -492,6 +492,11 @@ static int __init do_early_param(char *param, char *val) return 0; } +void __init parse_early_options(char *cmdline) +{ + parse_args("early options", cmdline, NULL, 0, do_early_param); +} + /* Arch code calls this early on, or if not, just before other parsing. */ void __init parse_early_param(void) { @@ -503,7 +508,7 @@ void __init parse_early_param(void) /* All fall through to do_early_param. */ strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE); - parse_args("early options", tmp_cmdline, NULL, 0, do_early_param); + parse_early_options(tmp_cmdline); done = 1; } |
