From d7b1956fed33d30c4815e848fd7a143722916868 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 19 Jan 2009 20:55:50 +0100 Subject: [PATCH] DMI: Introduce dmi_first_match to make the interface more flexible Some notebooks from HP have the problem that their BIOSes attempt to spin down hard drives before entering ACPI system states S4 and S5. This leads to a yo-yo effect during system power-off shutdown and the last phase of hibernation when the disk is first spun down by the kernel and then almost immediately turned on and off by the BIOS. This, in turn, may result in shortening the disk's life times. To prevent this from happening we can blacklist the affected systems using DMI information. However, only the on-board controlles should be blacklisted and their PCI slot numbers can be used for this purpose. Unfortunately the existing interface for checking DMI information of the system is not very convenient for this purpose, because to use it, we would have to define special callback functions or create a separate struct dmi_system_id table for each blacklisted system. To overcome this difficulty introduce a new function dmi_first_match() returning a pointer to the first entry in an array of struct dmi_system_id elements that matches the system DMI information. Then, we can use this pointer to access the entry's .driver_data field containing the additional information, such as the PCI slot number, allowing us to do the desired blacklisting. Signed-off-by: Rafael J. Wysocki Signed-off-by: Jeff Garzik --- drivers/firmware/dmi_scan.c | 74 +++++++++++++++++++++++++++---------- include/linux/dmi.h | 1 + 2 files changed, 56 insertions(+), 19 deletions(-) diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c index d76adfea5df..8f0f7c44930 100644 --- a/drivers/firmware/dmi_scan.c +++ b/drivers/firmware/dmi_scan.c @@ -414,6 +414,29 @@ void __init dmi_scan_machine(void) dmi_initialized = 1; } +/** + * dmi_matches - check if dmi_system_id structure matches system DMI data + * @dmi: pointer to the dmi_system_id structure to check + */ +static bool dmi_matches(const struct dmi_system_id *dmi) +{ + int i; + + WARN(!dmi_initialized, KERN_ERR "dmi check: not initialized yet.\n"); + + for (i = 0; i < ARRAY_SIZE(dmi->matches); i++) { + int s = dmi->matches[i].slot; + if (s == DMI_NONE) + continue; + if (dmi_ident[s] + && strstr(dmi_ident[s], dmi->matches[i].substr)) + continue; + /* No match */ + return false; + } + return true; +} + /** * dmi_check_system - check system DMI data * @list: array of dmi_system_id structures to match against @@ -429,31 +452,44 @@ void __init dmi_scan_machine(void) */ int dmi_check_system(const struct dmi_system_id *list) { - int i, count = 0; - const struct dmi_system_id *d = list; - - WARN(!dmi_initialized, KERN_ERR "dmi check: not initialized yet.\n"); - - while (d->ident) { - for (i = 0; i < ARRAY_SIZE(d->matches); i++) { - int s = d->matches[i].slot; - if (s == DMI_NONE) - continue; - if (dmi_ident[s] && strstr(dmi_ident[s], d->matches[i].substr)) - continue; - /* No match */ - goto fail; + int count = 0; + const struct dmi_system_id *d; + + for (d = list; d->ident; d++) + if (dmi_matches(d)) { + count++; + if (d->callback && d->callback(d)) + break; } - count++; - if (d->callback && d->callback(d)) - break; -fail: d++; - } return count; } EXPORT_SYMBOL(dmi_check_system); +/** + * dmi_first_match - find dmi_system_id structure matching system DMI data + * @list: array of dmi_system_id structures to match against + * All non-null elements of the list must match + * their slot's (field index's) data (i.e., each + * list string must be a substring of the specified + * DMI slot's string data) to be considered a + * successful match. + * + * Walk the blacklist table until the first match is found. Return the + * pointer to the matching entry or NULL if there's no match. + */ +const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list) +{ + const struct dmi_system_id *d; + + for (d = list; d->ident; d++) + if (dmi_matches(d)) + return d; + + return NULL; +} +EXPORT_SYMBOL(dmi_first_match); + /** * dmi_get_system_info - return DMI data value * @field: data index (see enum dmi_field) diff --git a/include/linux/dmi.h b/include/linux/dmi.h index 34161907b2f..aea23105d3e 100644 --- a/include/linux/dmi.h +++ b/include/linux/dmi.h @@ -38,6 +38,7 @@ struct dmi_device { #ifdef CONFIG_DMI extern int dmi_check_system(const struct dmi_system_id *list); +const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list); extern const char * dmi_get_system_info(int field); extern const struct dmi_device * dmi_find_device(int type, const char *name, const struct dmi_device *from); -- 2.41.0