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On Ampere Altra, PCIe hotplug is handled through ACPI. A side interface is also present to request system firmware control of the hotplug Attention Indicators. Add an ACPI PCI Hotplug companion driver to support Attention Indicator control. Link: https://lore.kernel.org/r/20230930002036.6491-2-scott@os.amperecomputing.com Signed-off-by: D Scott Phillips <scott@os.amperecomputing.com> [bhelgaas: mask domain to low 4 bits] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: "Rafael J. Wysocki" <rafael@kernel.org>
128 lines
2.9 KiB
C
128 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* ACPI PCI Hot Plug Extension for Ampere Altra. Allows control of
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* attention LEDs via requests to system firmware.
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*
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* Copyright (C) 2023 Ampere Computing LLC
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*/
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#define pr_fmt(fmt) "acpiphp_ampere_altra: " fmt
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/pci.h>
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#include <linux/pci_hotplug.h>
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#include <linux/platform_device.h>
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#include "acpiphp.h"
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#define HANDLE_OPEN 0xb0200000
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#define HANDLE_CLOSE 0xb0300000
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#define REQUEST 0xf0700000
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#define LED_CMD 0x00000004
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#define LED_ATTENTION 0x00000002
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#define LED_SET_ON 0x00000001
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#define LED_SET_OFF 0x00000002
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#define LED_SET_BLINK 0x00000003
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static u32 led_service_id[4];
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static int led_status(u8 status)
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{
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switch (status) {
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case 1: return LED_SET_ON;
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case 2: return LED_SET_BLINK;
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default: return LED_SET_OFF;
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}
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}
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static int set_attention_status(struct hotplug_slot *slot, u8 status)
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{
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struct arm_smccc_res res;
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struct pci_bus *bus;
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struct pci_dev *root_port;
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unsigned long flags;
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u32 handle;
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int ret = 0;
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bus = slot->pci_slot->bus;
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root_port = pcie_find_root_port(bus->self);
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if (!root_port)
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return -ENODEV;
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local_irq_save(flags);
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arm_smccc_smc(HANDLE_OPEN, led_service_id[0], led_service_id[1],
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led_service_id[2], led_service_id[3], 0, 0, 0, &res);
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if (res.a0) {
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ret = -ENODEV;
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goto out;
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}
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handle = res.a1 & 0xffff0000;
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arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
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(PCI_SLOT(root_port->devfn) << 4) | (pci_domain_nr(bus) & 0xf),
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0, 0, handle, &res);
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if (res.a0)
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ret = -ENODEV;
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arm_smccc_smc(HANDLE_CLOSE, handle, 0, 0, 0, 0, 0, 0, &res);
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out:
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local_irq_restore(flags);
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return ret;
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}
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static int get_attention_status(struct hotplug_slot *slot, u8 *status)
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{
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return -EINVAL;
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}
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static struct acpiphp_attention_info ampere_altra_attn = {
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.set_attn = set_attention_status,
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.get_attn = get_attention_status,
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.owner = THIS_MODULE,
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};
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static int altra_led_probe(struct platform_device *pdev)
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{
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struct fwnode_handle *fwnode = dev_fwnode(&pdev->dev);
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int ret;
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ret = fwnode_property_read_u32_array(fwnode, "uuid", led_service_id, 4);
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if (ret) {
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dev_err(&pdev->dev, "can't find uuid\n");
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return ret;
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}
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ret = acpiphp_register_attention(&ere_altra_attn);
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if (ret) {
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dev_err(&pdev->dev, "can't register driver\n");
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return ret;
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}
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return 0;
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}
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static void altra_led_remove(struct platform_device *pdev)
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{
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acpiphp_unregister_attention(&ere_altra_attn);
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}
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static const struct acpi_device_id altra_led_ids[] = {
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{ "AMPC0008", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(acpi, altra_led_ids);
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static struct platform_driver altra_led_driver = {
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.driver = {
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.name = "ampere-altra-leds",
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.acpi_match_table = altra_led_ids,
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},
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.probe = altra_led_probe,
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.remove_new = altra_led_remove,
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};
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module_platform_driver(altra_led_driver);
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MODULE_AUTHOR("D Scott Phillips <scott@os.amperecomputing.com>");
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MODULE_LICENSE("GPL");
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