MIPS: Malta: add suspend state entry code
This patch introduces code which will enter a suspend state via the
PIIX4. This can only be done when PCI support is enabled since it
requires access to PCI I/O space and the generation of a special cycle
on the PCI bus. In cases where PCI is disabled the mips_pm_suspend
function will simply always return an error.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6905/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mti-malta/malta-pm.c b/arch/mips/mti-malta/malta-pm.c
new file mode 100644
index 0000000..c1e456c
--- /dev/null
+++ b/arch/mips/mti-malta/malta-pm.c
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2014 Imagination Technologies
+ * Author: Paul Burton <paul.burton@imgtec.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/pci.h>
+
+#include <asm/mach-malta/malta-pm.h>
+
+static struct pci_bus *pm_pci_bus;
+static resource_size_t pm_io_offset;
+
+int mips_pm_suspend(unsigned state)
+{
+ int spec_devid;
+ u16 sts;
+
+ if (!pm_pci_bus || !pm_io_offset)
+ return -ENODEV;
+
+ /* Ensure the power button status is clear */
+ while (1) {
+ sts = inw(pm_io_offset + PIIX4_FUNC3IO_PMSTS);
+ if (!(sts & PIIX4_FUNC3IO_PMSTS_PWRBTN_STS))
+ break;
+ outw(sts, pm_io_offset + PIIX4_FUNC3IO_PMSTS);
+ }
+
+ /* Enable entry to suspend */
+ outw(state | PIIX4_FUNC3IO_PMCNTRL_SUS_EN,
+ pm_io_offset + PIIX4_FUNC3IO_PMCNTRL);
+
+ /* If the special cycle occurs too soon this doesn't work... */
+ mdelay(10);
+
+ /*
+ * The PIIX4 will enter the suspend state only after seeing a special
+ * cycle with the correct magic data on the PCI bus. Generate that
+ * cycle now.
+ */
+ spec_devid = PCI_DEVID(0, PCI_DEVFN(0x1f, 0x7));
+ pci_bus_write_config_dword(pm_pci_bus, spec_devid, 0,
+ PIIX4_SUSPEND_MAGIC);
+
+ /* Give the system some time to power down */
+ mdelay(1000);
+
+ return 0;
+}
+
+static int __init malta_pm_setup(void)
+{
+ struct pci_dev *dev;
+ int res, io_region = PCI_BRIDGE_RESOURCES;
+
+ /* Find a reference to the PCI bus */
+ pm_pci_bus = pci_find_next_bus(NULL);
+ if (!pm_pci_bus) {
+ pr_warn("malta-pm: failed to find reference to PCI bus\n");
+ return -ENODEV;
+ }
+
+ /* Find the PIIX4 PM device */
+ dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
+ PCI_DEVICE_ID_INTEL_82371AB_3, PCI_ANY_ID,
+ PCI_ANY_ID, NULL);
+ if (!dev) {
+ pr_warn("malta-pm: failed to find PIIX4 PM\n");
+ return -ENODEV;
+ }
+
+ /* Request access to the PIIX4 PM IO registers */
+ res = pci_request_region(dev, io_region, "PIIX4 PM IO registers");
+ if (res) {
+ pr_warn("malta-pm: failed to request PM IO registers (%d)\n",
+ res);
+ pci_dev_put(dev);
+ return -ENODEV;
+ }
+
+ /* Find the offset to the PIIX4 PM IO registers */
+ pm_io_offset = pci_resource_start(dev, io_region);
+
+ pci_dev_put(dev);
+ return 0;
+}
+
+late_initcall(malta_pm_setup);
