From d8441ea27ed1253f17f05f30057853a95a28b4c7 Mon Sep 17 00:00:00 2001 From: Simon Glass Date: Wed, 5 Oct 2016 20:42:16 -0600 Subject: [PATCH] dm: stdio: Allow lazy probing of video devices At present all video devices are probed on start-up. It would be better to probe a device only when it is needed. This can happen if it is referenced in the stdout environment variable, for example. Add support for this by searching for a suitable device when needed, probing it, and finding the stdio device it creates. Signed-off-by: Simon Glass Reviewed-by: Bin Meng --- common/stdio.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 83 insertions(+), 4 deletions(-) diff --git a/common/stdio.c b/common/stdio.c index f99cfe7..ab9b05d 100644 --- a/common/stdio.c +++ b/common/stdio.c @@ -121,19 +121,87 @@ struct list_head* stdio_get_list(void) return &(devs.list); } +#ifdef CONFIG_DM_VIDEO +/** + * stdio_probe_device() - Find a device which provides the given stdio device + * + * This looks for a device of the given uclass which provides a particular + * stdio device. It is currently really only useful for UCLASS_VIDEO. + * + * Ultimately we want to be able to probe a device by its stdio name. At + * present devices register in their probe function (for video devices this + * is done in vidconsole_post_probe()) and we don't know what name they will + * use until they do so. + * TODO(sjg@chromium.org): We should be able to determine the name before + * probing, and probe the required device. + * + * @name: stdio device name (e.g. "vidconsole") + * id: Uclass ID of device to look for (e.g. UCLASS_VIDEO) + * @sdevp: Returns stdout device, if found, else NULL + * @return 0 if found, -ENOENT if no device found with that name, other -ve + * on other error + */ +static int stdio_probe_device(const char *name, enum uclass_id id, + struct stdio_dev **sdevp) +{ + struct stdio_dev *sdev; + struct udevice *dev; + int seq, ret; + + *sdevp = NULL; + seq = trailing_strtoln(name, NULL); + if (seq == -1) + ret = uclass_first_device_err(id, &dev); + else + ret = uclass_get_device_by_seq(id, seq, &dev); + if (ret) { + debug("No %s device for seq %d (%s)\n", uclass_get_name(id), + seq, name); + return ret; + } + /* The device should be be the last one registered */ + sdev = list_empty(&devs.list) ? NULL : + list_last_entry(&devs.list, struct stdio_dev, list); + if (!sdev || strcmp(sdev->name, name)) { + debug("Device '%s' did not register with stdio as '%s'\n", + dev->name, name); + return -ENOENT; + } + *sdevp = sdev; + + return 0; +} +#endif + struct stdio_dev* stdio_get_by_name(const char *name) { struct list_head *pos; - struct stdio_dev *dev; + struct stdio_dev *sdev; if(!name) return NULL; list_for_each(pos, &(devs.list)) { - dev = list_entry(pos, struct stdio_dev, list); - if(strcmp(dev->name, name) == 0) - return dev; + sdev = list_entry(pos, struct stdio_dev, list); + if (strcmp(sdev->name, name) == 0) + return sdev; } +#ifdef CONFIG_DM_VIDEO + /* + * We did not find a suitable stdio device. If there is a video + * driver with a name starting with 'vidconsole', we can try probing + * that in the hope that it will produce the required stdio device. + * + * This function is sometimes called with the entire value of + * 'stdout', which may include a list of devices separate by commas. + * Obviously this is not going to work, so we ignore that case. The + * call path in that case is console_init_r() -> search_device() -> + * stdio_get_by_name(). + */ + if (!strncmp(name, "vidconsole", 10) && !strchr(name, ',') && + !stdio_probe_device(name, UCLASS_VIDEO, &sdev)) + return sdev; +#endif return NULL; } @@ -282,6 +350,16 @@ int stdio_add_devices(void) #endif #endif #ifdef CONFIG_DM_VIDEO + /* + * If the console setting is not in environment variables then + * console_init_r() will not be calling iomux_doenv() (which calls + * search_device()). So we will not dynamically add devices by + * calling stdio_probe_device(). + * + * So just probe all video devices now so that whichever one is + * required will be available. + */ +#ifndef CONFIG_SYS_CONSOLE_IS_IN_ENV struct udevice *vdev; # ifndef CONFIG_DM_KEYBOARD int ret; @@ -293,6 +371,7 @@ int stdio_add_devices(void) ; if (ret) printf("%s: Video device failed (ret=%d)\n", __func__, ret); +#endif /* !CONFIG_SYS_CONSOLE_IS_IN_ENV */ #else # if defined(CONFIG_LCD) drv_lcd_init (); -- 2.7.4