/*
 * Copyright (c) 2010 Red Hat Inc.
 * Author : Dave Airlie <airlied@redhat.com>
 *
 * Licensed under GPLv2
 *
 * ATPX support for both Intel/ATI
 */
#include <linux/vga_switcheroo.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/pci.h>

#include "amdgpu_acpi.h"

struct amdgpu_atpx_functions {
        bool px_params;
        bool power_cntl;
        bool disp_mux_cntl;
        bool i2c_mux_cntl;
        bool switch_start;
        bool switch_end;
        bool disp_connectors_mapping;
        bool disp_detetion_ports;
};

struct amdgpu_atpx {
        acpi_handle handle;
        struct amdgpu_atpx_functions functions;
};

static struct amdgpu_atpx_priv {
        bool atpx_detected;
        /* handle for device - and atpx */
        acpi_handle dhandle;
        acpi_handle other_handle;
        struct amdgpu_atpx atpx;
} amdgpu_atpx_priv;

struct atpx_verify_interface {
        u16 size;               /* structure size in bytes (includes size field) */
        u16 version;            /* version */
        u32 function_bits;      /* supported functions bit vector */
} __packed;

struct atpx_px_params {
        u16 size;               /* structure size in bytes (includes size field) */
        u32 valid_flags;        /* which flags are valid */
        u32 flags;              /* flags */
} __packed;

struct atpx_power_control {
        u16 size;
        u8 dgpu_state;
} __packed;

struct atpx_mux {
        u16 size;
        u16 mux;
} __packed;

bool amdgpu_has_atpx(void) {
        return amdgpu_atpx_priv.atpx_detected;
}

/**
 * amdgpu_atpx_call - call an ATPX method
 *
 * @handle: acpi handle
 * @function: the ATPX function to execute
 * @params: ATPX function params
 *
 * Executes the requested ATPX function (all asics).
 * Returns a pointer to the acpi output buffer.
 */
static union acpi_object *amdgpu_atpx_call(acpi_handle handle, int function,
                                           struct acpi_buffer *params)
{
        acpi_status status;
        union acpi_object atpx_arg_elements[2];
        struct acpi_object_list atpx_arg;
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

        atpx_arg.count = 2;
        atpx_arg.pointer = &atpx_arg_elements[0];

        atpx_arg_elements[0].type = ACPI_TYPE_INTEGER;
        atpx_arg_elements[0].integer.value = function;

        if (params) {
                atpx_arg_elements[1].type = ACPI_TYPE_BUFFER;
                atpx_arg_elements[1].buffer.length = params->length;
                atpx_arg_elements[1].buffer.pointer = params->pointer;
        } else {
                /* We need a second fake parameter */
                atpx_arg_elements[1].type = ACPI_TYPE_INTEGER;
                atpx_arg_elements[1].integer.value = 0;
        }

        status = acpi_evaluate_object(handle, NULL, &atpx_arg, &buffer);

        /* Fail only if calling the method fails and ATPX is supported */
        if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
                printk("failed to evaluate ATPX got %s\n",
                       acpi_format_exception(status));
                kfree(buffer.pointer);
                return NULL;
        }

        return buffer.pointer;
}

/**
 * amdgpu_atpx_parse_functions - parse supported functions
 *
 * @f: supported functions struct
 * @mask: supported functions mask from ATPX
 *
 * Use the supported functions mask from ATPX function
 * ATPX_FUNCTION_VERIFY_INTERFACE to determine what functions
 * are supported (all asics).
 */
static void amdgpu_atpx_parse_functions(struct amdgpu_atpx_functions *f, u32 mask)
{
        f->px_params = mask & ATPX_GET_PX_PARAMETERS_SUPPORTED;
        f->power_cntl = mask & ATPX_POWER_CONTROL_SUPPORTED;
        f->disp_mux_cntl = mask & ATPX_DISPLAY_MUX_CONTROL_SUPPORTED;
        f->i2c_mux_cntl = mask & ATPX_I2C_MUX_CONTROL_SUPPORTED;
        f->switch_start = mask & ATPX_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION_SUPPORTED;
        f->switch_end = mask & ATPX_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION_SUPPORTED;
        f->disp_connectors_mapping = mask & ATPX_GET_DISPLAY_CONNECTORS_MAPPING_SUPPORTED;
        f->disp_detetion_ports = mask & ATPX_GET_DISPLAY_DETECTION_PORTS_SUPPORTED;
}

/**
 * amdgpu_atpx_validate_functions - validate ATPX functions
 *
 * @atpx: amdgpu atpx struct
 *
 * Validate that required functions are enabled (all asics).
 * returns 0 on success, error on failure.
 */
static int amdgpu_atpx_validate(struct amdgpu_atpx *atpx)
{
        /* make sure required functions are enabled */
        /* dGPU power control is required */
        atpx->functions.power_cntl = true;

        if (atpx->functions.px_params) {
                union acpi_object *info;
                struct atpx_px_params output;
                size_t size;
                u32 valid_bits;

                info = amdgpu_atpx_call(atpx->handle, ATPX_FUNCTION_GET_PX_PARAMETERS, NULL);
                if (!info)
                        return -EIO;

                memset(&output, 0, sizeof(output));

                size = *(u16 *) info->buffer.pointer;
                if (size < 10) {
                        printk("ATPX buffer is too small: %zu\n", size);
                        kfree(info);
                        return -EINVAL;
                }
                size = min(sizeof(output), size);

                memcpy(&output, info->buffer.pointer, size);

                valid_bits = output.flags & output.valid_flags;
                /* if separate mux flag is set, mux controls are required */
                if (valid_bits & ATPX_SEPARATE_MUX_FOR_I2C) {
                        atpx->functions.i2c_mux_cntl = true;
                        atpx->functions.disp_mux_cntl = true;
                }
                /* if any outputs are muxed, mux controls are required */
                if (valid_bits & (ATPX_CRT1_RGB_SIGNAL_MUXED |
                                  ATPX_TV_SIGNAL_MUXED |
                                  ATPX_DFP_SIGNAL_MUXED))
                        atpx->functions.disp_mux_cntl = true;

                kfree(info);
        }
        return 0;
}

/**
 * amdgpu_atpx_verify_interface - verify ATPX
 *
 * @atpx: amdgpu atpx struct
 *
 * Execute the ATPX_FUNCTION_VERIFY_INTERFACE ATPX function
 * to initialize ATPX and determine what features are supported
 * (all asics).
 * returns 0 on success, error on failure.
 */
static int amdgpu_atpx_verify_interface(struct amdgpu_atpx *atpx)
{
        union acpi_object *info;
        struct atpx_verify_interface output;
        size_t size;
        int err = 0;

        info = amdgpu_atpx_call(atpx->handle, ATPX_FUNCTION_VERIFY_INTERFACE, NULL);
        if (!info)
                return -EIO;

        memset(&output, 0, sizeof(output));

        size = *(u16 *) info->buffer.pointer;
        if (size < 8) {
                printk("ATPX buffer is too small: %zu\n", size);
                err = -EINVAL;
                goto out;
        }
        size = min(sizeof(output), size);

        memcpy(&output, info->buffer.pointer, size);

        /* TODO: check version? */
        printk("ATPX version %u, functions 0x%08x\n",
               output.version, output.function_bits);

        amdgpu_atpx_parse_functions(&atpx->functions, output.function_bits);

out:
        kfree(info);
        return err;
}

/**
 * amdgpu_atpx_set_discrete_state - power up/down discrete GPU
 *
 * @atpx: atpx info struct
 * @state: discrete GPU state (0 = power down, 1 = power up)
 *
 * Execute the ATPX_FUNCTION_POWER_CONTROL ATPX function to
 * power down/up the discrete GPU (all asics).
 * Returns 0 on success, error on failure.
 */
static int amdgpu_atpx_set_discrete_state(struct amdgpu_atpx *atpx, u8 state)
{
        struct acpi_buffer params;
        union acpi_object *info;
        struct atpx_power_control input;

        if (atpx->functions.power_cntl) {
                input.size = 3;
                input.dgpu_state = state;
                params.length = input.size;
                params.pointer = &input;
                info = amdgpu_atpx_call(atpx->handle,
                                        ATPX_FUNCTION_POWER_CONTROL,
                                        &params);
                if (!info)
                        return -EIO;
                kfree(info);
        }
        return 0;
}

/**
 * amdgpu_atpx_switch_disp_mux - switch display mux
 *
 * @atpx: atpx info struct
 * @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
 *
 * Execute the ATPX_FUNCTION_DISPLAY_MUX_CONTROL ATPX function to
 * switch the display mux between the discrete GPU and integrated GPU
 * (all asics).
 * Returns 0 on success, error on failure.
 */
static int amdgpu_atpx_switch_disp_mux(struct amdgpu_atpx *atpx, u16 mux_id)
{
        struct acpi_buffer params;
        union acpi_object *info;
        struct atpx_mux input;

        if (atpx->functions.disp_mux_cntl) {
                input.size = 4;
                input.mux = mux_id;
                params.length = input.size;
                params.pointer = &input;
                info = amdgpu_atpx_call(atpx->handle,
                                        ATPX_FUNCTION_DISPLAY_MUX_CONTROL,
                                        &params);
                if (!info)
                        return -EIO;
                kfree(info);
        }
        return 0;
}

/**
 * amdgpu_atpx_switch_i2c_mux - switch i2c/hpd mux
 *
 * @atpx: atpx info struct
 * @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
 *
 * Execute the ATPX_FUNCTION_I2C_MUX_CONTROL ATPX function to
 * switch the i2c/hpd mux between the discrete GPU and integrated GPU
 * (all asics).
 * Returns 0 on success, error on failure.
 */
static int amdgpu_atpx_switch_i2c_mux(struct amdgpu_atpx *atpx, u16 mux_id)
{
        struct acpi_buffer params;
        union acpi_object *info;
        struct atpx_mux input;

        if (atpx->functions.i2c_mux_cntl) {
                input.size = 4;
                input.mux = mux_id;
                params.length = input.size;
                params.pointer = &input;
                info = amdgpu_atpx_call(atpx->handle,
                                        ATPX_FUNCTION_I2C_MUX_CONTROL,
                                        &params);
                if (!info)
                        return -EIO;
                kfree(info);
        }
        return 0;
}

/**
 * amdgpu_atpx_switch_start - notify the sbios of a GPU switch
 *
 * @atpx: atpx info struct
 * @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
 *
 * Execute the ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION ATPX
 * function to notify the sbios that a switch between the discrete GPU and
 * integrated GPU has begun (all asics).
 * Returns 0 on success, error on failure.
 */
static int amdgpu_atpx_switch_start(struct amdgpu_atpx *atpx, u16 mux_id)
{
        struct acpi_buffer params;
        union acpi_object *info;
        struct atpx_mux input;

        if (atpx->functions.switch_start) {
                input.size = 4;
                input.mux = mux_id;
                params.length = input.size;
                params.pointer = &input;
                info = amdgpu_atpx_call(atpx->handle,
                                        ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_START_NOTIFICATION,
                                        &params);
                if (!info)
                        return -EIO;
                kfree(info);
        }
        return 0;
}

/**
 * amdgpu_atpx_switch_end - notify the sbios of a GPU switch
 *
 * @atpx: atpx info struct
 * @mux_id: mux state (0 = integrated GPU, 1 = discrete GPU)
 *
 * Execute the ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION ATPX
 * function to notify the sbios that a switch between the discrete GPU and
 * integrated GPU has ended (all asics).
 * Returns 0 on success, error on failure.
 */
static int amdgpu_atpx_switch_end(struct amdgpu_atpx *atpx, u16 mux_id)
{
        struct acpi_buffer params;
        union acpi_object *info;
        struct atpx_mux input;

        if (atpx->functions.switch_end) {
                input.size = 4;
                input.mux = mux_id;
                params.length = input.size;
                params.pointer = &input;
                info = amdgpu_atpx_call(atpx->handle,
                                        ATPX_FUNCTION_GRAPHICS_DEVICE_SWITCH_END_NOTIFICATION,
                                        &params);
                if (!info)
                        return -EIO;
                kfree(info);
        }
        return 0;
}

/**
 * amdgpu_atpx_switchto - switch to the requested GPU
 *
 * @id: GPU to switch to
 *
 * Execute the necessary ATPX functions to switch between the discrete GPU and
 * integrated GPU (all asics).
 * Returns 0 on success, error on failure.
 */
static int amdgpu_atpx_switchto(enum vga_switcheroo_client_id id)
{
        u16 gpu_id;

        if (id == VGA_SWITCHEROO_IGD)
                gpu_id = ATPX_INTEGRATED_GPU;
        else
                gpu_id = ATPX_DISCRETE_GPU;

        amdgpu_atpx_switch_start(&amdgpu_atpx_priv.atpx, gpu_id);
        amdgpu_atpx_switch_disp_mux(&amdgpu_atpx_priv.atpx, gpu_id);
        amdgpu_atpx_switch_i2c_mux(&amdgpu_atpx_priv.atpx, gpu_id);
        amdgpu_atpx_switch_end(&amdgpu_atpx_priv.atpx, gpu_id);

        return 0;
}

/**
 * amdgpu_atpx_power_state - power down/up the requested GPU
 *
 * @id: GPU to power down/up
 * @state: requested power state (0 = off, 1 = on)
 *
 * Execute the necessary ATPX function to power down/up the discrete GPU
 * (all asics).
 * Returns 0 on success, error on failure.
 */
static int amdgpu_atpx_power_state(enum vga_switcheroo_client_id id,
                                   enum vga_switcheroo_state state)
{
        /* on w500 ACPI can't change intel gpu state */
        if (id == VGA_SWITCHEROO_IGD)
                return 0;

        amdgpu_atpx_set_discrete_state(&amdgpu_atpx_priv.atpx, state);
        return 0;
}

/**
 * amdgpu_atpx_pci_probe_handle - look up the ATPX handle
 *
 * @pdev: pci device
 *
 * Look up the ATPX handles (all asics).
 * Returns true if the handles are found, false if not.
 */
static bool amdgpu_atpx_pci_probe_handle(struct pci_dev *pdev)
{
        acpi_handle dhandle, atpx_handle;
        acpi_status status;

        dhandle = ACPI_HANDLE(&pdev->dev);
        if (!dhandle)
                return false;

        status = acpi_get_handle(dhandle, "ATPX", &atpx_handle);
        if (ACPI_FAILURE(status)) {
                amdgpu_atpx_priv.other_handle = dhandle;
                return false;
        }
        amdgpu_atpx_priv.dhandle = dhandle;
        amdgpu_atpx_priv.atpx.handle = atpx_handle;
        return true;
}

/**
 * amdgpu_atpx_init - verify the ATPX interface
 *
 * Verify the ATPX interface (all asics).
 * Returns 0 on success, error on failure.
 */
static int amdgpu_atpx_init(void)
{
        int r;

        /* set up the ATPX handle */
        r = amdgpu_atpx_verify_interface(&amdgpu_atpx_priv.atpx);
        if (r)
                return r;

        /* validate the atpx setup */
        r = amdgpu_atpx_validate(&amdgpu_atpx_priv.atpx);
        if (r)
                return r;

        return 0;
}

/**
 * amdgpu_atpx_get_client_id - get the client id
 *
 * @pdev: pci device
 *
 * look up whether we are the integrated or discrete GPU (all asics).
 * Returns the client id.
 */
static int amdgpu_atpx_get_client_id(struct pci_dev *pdev)
{
        if (amdgpu_atpx_priv.dhandle == ACPI_HANDLE(&pdev->dev))
                return VGA_SWITCHEROO_IGD;
        else
                return VGA_SWITCHEROO_DIS;
}

static const struct vga_switcheroo_handler amdgpu_atpx_handler = {
        .switchto = amdgpu_atpx_switchto,
        .power_state = amdgpu_atpx_power_state,
        .init = amdgpu_atpx_init,
        .get_client_id = amdgpu_atpx_get_client_id,
};

/**
 * amdgpu_atpx_detect - detect whether we have PX
 *
 * Check if we have a PX system (all asics).
 * Returns true if we have a PX system, false if not.
 */
static bool amdgpu_atpx_detect(void)
{
        char acpi_method_name[255] = { 0 };
        struct acpi_buffer buffer = {sizeof(acpi_method_name), acpi_method_name};
        struct pci_dev *pdev = NULL;
        bool has_atpx = false;
        int vga_count = 0;

        while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL) {
                vga_count++;

                has_atpx |= (amdgpu_atpx_pci_probe_handle(pdev) == true);
        }

        while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_OTHER << 8, pdev)) != NULL) {
                vga_count++;

                has_atpx |= (amdgpu_atpx_pci_probe_handle(pdev) == true);
        }

        if (has_atpx && vga_count == 2) {
                acpi_get_name(amdgpu_atpx_priv.atpx.handle, ACPI_FULL_PATHNAME, &buffer);
                printk(KERN_INFO "vga_switcheroo: detected switching method %s handle\n",
                       acpi_method_name);
                amdgpu_atpx_priv.atpx_detected = true;
                return true;
        }
        return false;
}

/**
 * amdgpu_register_atpx_handler - register with vga_switcheroo
 *
 * Register the PX callbacks with vga_switcheroo (all asics).
 */
void amdgpu_register_atpx_handler(void)
{
        bool r;

        /* detect if we have any ATPX + 2 VGA in the system */
        r = amdgpu_atpx_detect();
        if (!r)
                return;

        vga_switcheroo_register_handler(&amdgpu_atpx_handler);
}

/**
 * amdgpu_unregister_atpx_handler - unregister with vga_switcheroo
 *
 * Unregister the PX callbacks with vga_switcheroo (all asics).
 */
void amdgpu_unregister_atpx_handler(void)
{
        vga_switcheroo_unregister_handler();
}