// SPDX-License-Identifier: GPL-2.0
/*
 * Siemens SIMATIC IPC platform driver
 *
 * Copyright (c) Siemens AG, 2018-2021
 *
 * Authors:
 *  Henning Schild <henning.schild@siemens.com>
 *  Jan Kiszka <jan.kiszka@siemens.com>
 *  Gerd Haeussler <gerd.haeussler.ext@siemens.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/dmi.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/platform_data/x86/simatic-ipc.h>
#include <linux/platform_device.h>

static struct platform_device *ipc_led_platform_device;
static struct platform_device *ipc_wdt_platform_device;

static const struct dmi_system_id simatic_ipc_whitelist[] = {
	{
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "SIEMENS AG"),
		},
	},
	{}
};

static struct simatic_ipc_platform platform_data;

static struct {
	u32 station_id;
	u8 led_mode;
	u8 wdt_mode;
} device_modes[] = {
	{SIMATIC_IPC_IPC127E, SIMATIC_IPC_DEVICE_127E, SIMATIC_IPC_DEVICE_NONE},
	{SIMATIC_IPC_IPC227D, SIMATIC_IPC_DEVICE_227D, SIMATIC_IPC_DEVICE_NONE},
	{SIMATIC_IPC_IPC227E, SIMATIC_IPC_DEVICE_427E, SIMATIC_IPC_DEVICE_227E},
	{SIMATIC_IPC_IPC277E, SIMATIC_IPC_DEVICE_NONE, SIMATIC_IPC_DEVICE_227E},
	{SIMATIC_IPC_IPC427D, SIMATIC_IPC_DEVICE_427E, SIMATIC_IPC_DEVICE_NONE},
	{SIMATIC_IPC_IPC427E, SIMATIC_IPC_DEVICE_427E, SIMATIC_IPC_DEVICE_427E},
	{SIMATIC_IPC_IPC477E, SIMATIC_IPC_DEVICE_NONE, SIMATIC_IPC_DEVICE_427E},
};

static int register_platform_devices(u32 station_id)
{
	u8 ledmode = SIMATIC_IPC_DEVICE_NONE;
	u8 wdtmode = SIMATIC_IPC_DEVICE_NONE;
	int i;

	platform_data.devmode = SIMATIC_IPC_DEVICE_NONE;

	for (i = 0; i < ARRAY_SIZE(device_modes); i++) {
		if (device_modes[i].station_id == station_id) {
			ledmode = device_modes[i].led_mode;
			wdtmode = device_modes[i].wdt_mode;
			break;
		}
	}

	if (ledmode != SIMATIC_IPC_DEVICE_NONE) {
		platform_data.devmode = ledmode;
		ipc_led_platform_device =
			platform_device_register_data(NULL,
				KBUILD_MODNAME "_leds", PLATFORM_DEVID_NONE,
				&platform_data,
				sizeof(struct simatic_ipc_platform));
		if (IS_ERR(ipc_led_platform_device))
			return PTR_ERR(ipc_led_platform_device);

		pr_debug("device=%s created\n",
			 ipc_led_platform_device->name);
	}

	if (wdtmode != SIMATIC_IPC_DEVICE_NONE) {
		platform_data.devmode = wdtmode;
		ipc_wdt_platform_device =
			platform_device_register_data(NULL,
				KBUILD_MODNAME "_wdt", PLATFORM_DEVID_NONE,
				&platform_data,
				sizeof(struct simatic_ipc_platform));
		if (IS_ERR(ipc_wdt_platform_device))
			return PTR_ERR(ipc_wdt_platform_device);

		pr_debug("device=%s created\n",
			 ipc_wdt_platform_device->name);
	}

	if (ledmode == SIMATIC_IPC_DEVICE_NONE &&
	    wdtmode == SIMATIC_IPC_DEVICE_NONE) {
		pr_warn("unsupported IPC detected, station id=%08x\n",
			station_id);
		return -EINVAL;
	}

	return 0;
}

/* FIXME: this should eventually be done with generic P2SB discovery code
 * the individual drivers for watchdogs and LEDs access memory that implements
 * GPIO, but pinctrl will not come up because of missing ACPI entries
 *
 * While there is no conflict a cleaner solution would be to somehow bring up
 * pinctrl even with these ACPI entries missing, and base the drivers on pinctrl.
 * After which the following function could be dropped, together with the code
 * poking the memory.
 */
/*
 * Get membase address from PCI, used in leds and wdt module. Here we read
 * the bar0. The final address calculation is done in the appropriate modules
 */
u32 simatic_ipc_get_membase0(unsigned int p2sb)
{
	struct pci_bus *bus;
	u32 bar0 = 0;
	/*
	 * The GPIO memory is in bar0 of the hidden P2SB device.
	 * Unhide the device to have a quick look at it, before we hide it
	 * again.
	 * Also grab the pci rescan lock so that device does not get discovered
	 * and remapped while it is visible.
	 * This code is inspired by drivers/mfd/lpc_ich.c
	 */
	bus = pci_find_bus(0, 0);
	pci_lock_rescan_remove();
	pci_bus_write_config_byte(bus, p2sb, 0xE1, 0x0);
	pci_bus_read_config_dword(bus, p2sb, PCI_BASE_ADDRESS_0, &bar0);

	bar0 &= ~0xf;
	pci_bus_write_config_byte(bus, p2sb, 0xE1, 0x1);
	pci_unlock_rescan_remove();

	return bar0;
}
EXPORT_SYMBOL(simatic_ipc_get_membase0);

static int __init simatic_ipc_init_module(void)
{
	const struct dmi_system_id *match;
	u32 station_id;
	int err;

	match = dmi_first_match(simatic_ipc_whitelist);
	if (!match)
		return 0;

	err = dmi_walk(simatic_ipc_find_dmi_entry_helper, &station_id);

	if (err || station_id == SIMATIC_IPC_INVALID_STATION_ID) {
		pr_warn("DMI entry %d not found\n", SIMATIC_IPC_DMI_ENTRY_OEM);
		return 0;
	}

	return register_platform_devices(station_id);
}

static void __exit simatic_ipc_exit_module(void)
{
	platform_device_unregister(ipc_led_platform_device);
	ipc_led_platform_device = NULL;

	platform_device_unregister(ipc_wdt_platform_device);
	ipc_wdt_platform_device = NULL;
}

module_init(simatic_ipc_init_module);
module_exit(simatic_ipc_exit_module);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Gerd Haeussler <gerd.haeussler.ext@siemens.com>");
MODULE_ALIAS("dmi:*:svnSIEMENSAG:*");