b6911bba59
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>
96 lines
2.4 KiB
C
96 lines
2.4 KiB
C
/*
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* Copyright (C) 2014 Imagination Technologies
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* Author: Paul Burton <paul.burton@imgtec.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <linux/pci.h>
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#include <asm/mach-malta/malta-pm.h>
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static struct pci_bus *pm_pci_bus;
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static resource_size_t pm_io_offset;
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int mips_pm_suspend(unsigned state)
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{
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int spec_devid;
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u16 sts;
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if (!pm_pci_bus || !pm_io_offset)
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return -ENODEV;
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/* Ensure the power button status is clear */
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while (1) {
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sts = inw(pm_io_offset + PIIX4_FUNC3IO_PMSTS);
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if (!(sts & PIIX4_FUNC3IO_PMSTS_PWRBTN_STS))
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break;
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outw(sts, pm_io_offset + PIIX4_FUNC3IO_PMSTS);
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}
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/* Enable entry to suspend */
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outw(state | PIIX4_FUNC3IO_PMCNTRL_SUS_EN,
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pm_io_offset + PIIX4_FUNC3IO_PMCNTRL);
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/* If the special cycle occurs too soon this doesn't work... */
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mdelay(10);
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/*
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* The PIIX4 will enter the suspend state only after seeing a special
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* cycle with the correct magic data on the PCI bus. Generate that
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* cycle now.
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*/
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spec_devid = PCI_DEVID(0, PCI_DEVFN(0x1f, 0x7));
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pci_bus_write_config_dword(pm_pci_bus, spec_devid, 0,
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PIIX4_SUSPEND_MAGIC);
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/* Give the system some time to power down */
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mdelay(1000);
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return 0;
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}
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static int __init malta_pm_setup(void)
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{
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struct pci_dev *dev;
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int res, io_region = PCI_BRIDGE_RESOURCES;
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/* Find a reference to the PCI bus */
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pm_pci_bus = pci_find_next_bus(NULL);
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if (!pm_pci_bus) {
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pr_warn("malta-pm: failed to find reference to PCI bus\n");
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return -ENODEV;
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}
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/* Find the PIIX4 PM device */
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dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
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PCI_DEVICE_ID_INTEL_82371AB_3, PCI_ANY_ID,
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PCI_ANY_ID, NULL);
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if (!dev) {
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pr_warn("malta-pm: failed to find PIIX4 PM\n");
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return -ENODEV;
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}
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/* Request access to the PIIX4 PM IO registers */
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res = pci_request_region(dev, io_region, "PIIX4 PM IO registers");
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if (res) {
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pr_warn("malta-pm: failed to request PM IO registers (%d)\n",
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res);
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pci_dev_put(dev);
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return -ENODEV;
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}
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/* Find the offset to the PIIX4 PM IO registers */
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pm_io_offset = pci_resource_start(dev, io_region);
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pci_dev_put(dev);
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return 0;
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}
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late_initcall(malta_pm_setup);
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