// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Support for the OLPC DCON and OLPC EC access
 *
 * Copyright © 2006  Advanced Micro Devices, Inc.
 * Copyright © 2007-2008  Andres Salomon <dilinger@debian.org>
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/string.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/syscore_ops.h>
#include <linux/mutex.h>
#include <linux/olpc-ec.h>

#include <asm/geode.h>
#include <asm/setup.h>
#include <asm/olpc.h>
#include <asm/olpc_ofw.h>

struct olpc_platform_t olpc_platform_info;
EXPORT_SYMBOL_GPL(olpc_platform_info);

/* what the timeout *should* be (in ms) */
#define EC_BASE_TIMEOUT 20

/* the timeout that bugs in the EC might force us to actually use */
static int ec_timeout = EC_BASE_TIMEOUT;

static int __init olpc_ec_timeout_set(char *str)
{
        if (get_option(&str, &ec_timeout) != 1) {
                ec_timeout = EC_BASE_TIMEOUT;
                printk(KERN_ERR "olpc-ec:  invalid argument to "
                                "'olpc_ec_timeout=', ignoring!\n");
        }
        printk(KERN_DEBUG "olpc-ec:  using %d ms delay for EC commands.\n",
                        ec_timeout);
        return 1;
}
__setup("olpc_ec_timeout=", olpc_ec_timeout_set);

/*
 * These {i,o}bf_status functions return whether the buffers are full or not.
 */

static inline unsigned int ibf_status(unsigned int port)
{
        return !!(inb(port) & 0x02);
}

static inline unsigned int obf_status(unsigned int port)
{
        return inb(port) & 0x01;
}

#define wait_on_ibf(p, d) __wait_on_ibf(__LINE__, (p), (d))
static int __wait_on_ibf(unsigned int line, unsigned int port, int desired)
{
        unsigned int timeo;
        int state = ibf_status(port);

        for (timeo = ec_timeout; state != desired && timeo; timeo--) {
                mdelay(1);
                state = ibf_status(port);
        }

        if ((state == desired) && (ec_timeout > EC_BASE_TIMEOUT) &&
                        timeo < (ec_timeout - EC_BASE_TIMEOUT)) {
                printk(KERN_WARNING "olpc-ec:  %d: waited %u ms for IBF!\n",
                                line, ec_timeout - timeo);
        }

        return !(state == desired);
}

#define wait_on_obf(p, d) __wait_on_obf(__LINE__, (p), (d))
static int __wait_on_obf(unsigned int line, unsigned int port, int desired)
{
        unsigned int timeo;
        int state = obf_status(port);

        for (timeo = ec_timeout; state != desired && timeo; timeo--) {
                mdelay(1);
                state = obf_status(port);
        }

        if ((state == desired) && (ec_timeout > EC_BASE_TIMEOUT) &&
                        timeo < (ec_timeout - EC_BASE_TIMEOUT)) {
                printk(KERN_WARNING "olpc-ec:  %d: waited %u ms for OBF!\n",
                                line, ec_timeout - timeo);
        }

        return !(state == desired);
}

/*
 * This allows the kernel to run Embedded Controller commands.  The EC is
 * documented at <http://wiki.laptop.org/go/Embedded_controller>, and the
 * available EC commands are here:
 * <http://wiki.laptop.org/go/Ec_specification>.  Unfortunately, while
 * OpenFirmware's source is available, the EC's is not.
 */
static int olpc_xo1_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf,
                size_t outlen, void *arg)
{
        int ret = -EIO;
        int i;
        int restarts = 0;

        /* Clear OBF */
        for (i = 0; i < 10 && (obf_status(0x6c) == 1); i++)
                inb(0x68);
        if (i == 10) {
                printk(KERN_ERR "olpc-ec:  timeout while attempting to "
                                "clear OBF flag!\n");
                goto err;
        }

        if (wait_on_ibf(0x6c, 0)) {
                printk(KERN_ERR "olpc-ec:  timeout waiting for EC to "
                                "quiesce!\n");
                goto err;
        }

restart:
        /*
         * Note that if we time out during any IBF checks, that's a failure;
         * we have to return.  There's no way for the kernel to clear that.
         *
         * If we time out during an OBF check, we can restart the command;
         * reissuing it will clear the OBF flag, and we should be alright.
         * The OBF flag will sometimes misbehave due to what we believe
         * is a hardware quirk..
         */
        pr_devel("olpc-ec:  running cmd 0x%x\n", cmd);
        outb(cmd, 0x6c);

        if (wait_on_ibf(0x6c, 0)) {
                printk(KERN_ERR "olpc-ec:  timeout waiting for EC to read "
                                "command!\n");
                goto err;
        }

        if (inbuf && inlen) {
                /* write data to EC */
                for (i = 0; i < inlen; i++) {
                        pr_devel("olpc-ec:  sending cmd arg 0x%x\n", inbuf[i]);
                        outb(inbuf[i], 0x68);
                        if (wait_on_ibf(0x6c, 0)) {
                                printk(KERN_ERR "olpc-ec:  timeout waiting for"
                                                " EC accept data!\n");
                                goto err;
                        }
                }
        }
        if (outbuf && outlen) {
                /* read data from EC */
                for (i = 0; i < outlen; i++) {
                        if (wait_on_obf(0x6c, 1)) {
                                printk(KERN_ERR "olpc-ec:  timeout waiting for"
                                                " EC to provide data!\n");
                                if (restarts++ < 10)
                                        goto restart;
                                goto err;
                        }
                        outbuf[i] = inb(0x68);
                        pr_devel("olpc-ec:  received 0x%x\n", outbuf[i]);
                }
        }

        ret = 0;
err:
        return ret;
}

static bool __init check_ofw_architecture(struct device_node *root)
{
        const char *olpc_arch;
        int propsize;

        olpc_arch = of_get_property(root, "architecture", &propsize);
        return propsize == 5 && strncmp("OLPC", olpc_arch, 5) == 0;
}

static u32 __init get_board_revision(struct device_node *root)
{
        int propsize;
        const __be32 *rev;

        rev = of_get_property(root, "board-revision-int", &propsize);
        if (propsize != 4)
                return 0;

        return be32_to_cpu(*rev);
}

static bool __init platform_detect(void)
{
        struct device_node *root = of_find_node_by_path("/");
        bool success;

        if (!root)
                return false;

        success = check_ofw_architecture(root);
        if (success) {
                olpc_platform_info.boardrev = get_board_revision(root);
                olpc_platform_info.flags |= OLPC_F_PRESENT;

                pr_info("OLPC board revision %s%X\n",
                        ((olpc_platform_info.boardrev & 0xf) < 8) ? "pre" : "",
                        olpc_platform_info.boardrev >> 4);
        }

        of_node_put(root);
        return success;
}

static int __init add_xo1_platform_devices(void)
{
        struct platform_device *pdev;

        pdev = platform_device_register_simple("xo1-rfkill", -1, NULL, 0);
        if (IS_ERR(pdev))
                return PTR_ERR(pdev);

        pdev = platform_device_register_simple("olpc-xo1", -1, NULL, 0);

        return PTR_ERR_OR_ZERO(pdev);
}

static int olpc_xo1_ec_suspend(struct platform_device *pdev)
{
        /*
         * Squelch SCIs while suspended.  This is a fix for
         * <http://dev.laptop.org/ticket/1835>.
         */
        return olpc_ec_cmd(EC_SET_SCI_INHIBIT, NULL, 0, NULL, 0);
}

static int olpc_xo1_ec_resume(struct platform_device *pdev)
{
        /* Tell the EC to stop inhibiting SCIs */
        olpc_ec_cmd(EC_SET_SCI_INHIBIT_RELEASE, NULL, 0, NULL, 0);

        /*
         * Tell the wireless module to restart USB communication.
         * Must be done twice.
         */
        olpc_ec_cmd(EC_WAKE_UP_WLAN, NULL, 0, NULL, 0);
        olpc_ec_cmd(EC_WAKE_UP_WLAN, NULL, 0, NULL, 0);

        return 0;
}

static struct olpc_ec_driver ec_xo1_driver = {
        .suspend = olpc_xo1_ec_suspend,
        .resume = olpc_xo1_ec_resume,
        .ec_cmd = olpc_xo1_ec_cmd,
#ifdef CONFIG_OLPC_XO1_SCI
        /*
         * XO-1 EC wakeups are available when olpc-xo1-sci driver is
         * compiled in
         */
        .wakeup_available = true,
#endif
};

static struct olpc_ec_driver ec_xo1_5_driver = {
        .ec_cmd = olpc_xo1_ec_cmd,
#ifdef CONFIG_OLPC_XO15_SCI
        /*
         * XO-1.5 EC wakeups are available when olpc-xo15-sci driver is
         * compiled in
         */
        .wakeup_available = true,
#endif
};

static int __init olpc_init(void)
{
        int r = 0;

        if (!olpc_ofw_present() || !platform_detect())
                return 0;

        /* register the XO-1 and 1.5-specific EC handler */
        if (olpc_platform_info.boardrev < olpc_board_pre(0xd0)) /* XO-1 */
                olpc_ec_driver_register(&ec_xo1_driver, NULL);
        else
                olpc_ec_driver_register(&ec_xo1_5_driver, NULL);
        platform_device_register_simple("olpc-ec", -1, NULL, 0);

        /* assume B1 and above models always have a DCON */
        if (olpc_board_at_least(olpc_board(0xb1)))
                olpc_platform_info.flags |= OLPC_F_DCON;

#ifdef CONFIG_PCI_OLPC
        /* If the VSA exists let it emulate PCI, if not emulate in kernel.
         * XO-1 only. */
        if (olpc_platform_info.boardrev < olpc_board_pre(0xd0) &&
                        !cs5535_has_vsa2())
                x86_init.pci.arch_init = pci_olpc_init;
#endif

        if (olpc_platform_info.boardrev < olpc_board_pre(0xd0)) { /* XO-1 */
                r = add_xo1_platform_devices();
                if (r)
                        return r;
        }

        return 0;
}

postcore_initcall(olpc_init);