gpio: gpio-ich: Share ownership of GPIO groups

The ICH chips have their GPIO pins organized in 2 or 3 independent
groups of 32 GPIO pins. It can happen that the ACPI BIOS wants to make
use of pins in one group, preventing the OS to access these. This does
not prevent the OS from accessing the other group(s).

This is the case for example on my Asus Z8NA-D6 board. The ACPI BIOS
wants to control GPIO 18 (group 1), while I (the OS) need to control
GPIO 52 and 53 (group 2) for SMBus multiplexing.

So instead of checking for ACPI resource conflict on the whole I/O
range, check on a per-group basis, and consider it a success if at
least one of the groups is available for the OS to use.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Peter Tyser <ptyser@xes-inc.com>
Cc: Aaron Sierra <asierra@xes-inc.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 27 insertions, 2 deletions

diff --git a/drivers/mfd/lpc_ich.c b/drivers/mfd/lpc_ich.c
index 092ad4b44b6..d142622a3fb 100644
--- a/drivers/mfd/lpc_ich.c
+++ b/drivers/mfd/lpc_ich.c
@@ -683,6 +683,30 @@ static void __devinit lpc_ich_finalize_cell(struct mfd_cell *cell,
 	cell->pdata_size = sizeof(struct lpc_ich_info);
 }
 
+/*
+ * We don't check for resource conflict globally. There are 2 or 3 independent
+ * GPIO groups and it's enough to have access to one of these to instantiate
+ * the device.
+ */
+static int __devinit lpc_ich_check_conflict_gpio(struct resource *res)
+{
+	int ret;
+	u8 use_gpio = 0;
+
+	if (resource_size(res) >= 0x50 &&
+	    !acpi_check_region(res->start + 0x40, 0x10, "LPC ICH GPIO3"))
+		use_gpio |= 1 << 2;
+
+	if (!acpi_check_region(res->start + 0x30, 0x10, "LPC ICH GPIO2"))
+		use_gpio |= 1 << 1;
+
+	ret = acpi_check_region(res->start + 0x00, 0x30, "LPC ICH GPIO1");
+	if (!ret)
+		use_gpio |= 1 << 0;
+
+	return use_gpio ? use_gpio : ret;
+}
+
 static int __devinit lpc_ich_init_gpio(struct pci_dev *dev,
 				const struct pci_device_id *id)
 {
@@ -740,12 +764,13 @@ gpe0_done:
 		break;
 	}
 
-	ret = acpi_check_resource_conflict(res);
-	if (ret) {
+	ret = lpc_ich_check_conflict_gpio(res);
+	if (ret < 0) {
 		/* this isn't necessarily fatal for the GPIO */
 		acpi_conflict = true;
 		goto gpio_done;
 	}
+	lpc_chipset_info[id->driver_data].use_gpio = ret;
 	lpc_ich_enable_gpio_space(dev);
 
 	lpc_ich_finalize_cell(&lpc_ich_cells[LPC_GPIO], id);