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;
 }