/*
 * Atmel SAMA5D2-Compatible Shutdown Controller (SHDWC) driver.
 * Found on some SoCs as the sama5d2 (obviously).
 *
 * Copyright (C) 2015 Atmel Corporation,
 *                    Nicolas Ferre <nicolas.ferre@atmel.com>
 *
 * Evolved from driver at91-poweroff.c.
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2.  This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 *
 * TODO:
 * - addition to status of other wake-up inputs [1 - 15]
 * - Analog Comparator wake-up alarm
 * - Serial RX wake-up alarm
 * - low power debouncer
 */

#include <linux/clk.h>
#include <linux/clk/at91_pmc.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/printk.h>

#include <soc/at91/at91sam9_ddrsdr.h>

#define SLOW_CLOCK_FREQ 32768

#define AT91_SHDW_CR    0x00            /* Shut Down Control Register */
#define AT91_SHDW_SHDW          BIT(0)                  /* Shut Down command */
#define AT91_SHDW_KEY           (0xa5UL << 24)          /* KEY Password */

#define AT91_SHDW_MR    0x04            /* Shut Down Mode Register */
#define AT91_SHDW_WKUPDBC_SHIFT 24
#define AT91_SHDW_WKUPDBC_MASK  GENMASK(26, 24)
#define AT91_SHDW_WKUPDBC(x)    (((x) << AT91_SHDW_WKUPDBC_SHIFT) \
                                                & AT91_SHDW_WKUPDBC_MASK)

#define AT91_SHDW_SR    0x08            /* Shut Down Status Register */
#define AT91_SHDW_WKUPIS_SHIFT  16
#define AT91_SHDW_WKUPIS_MASK   GENMASK(31, 16)
#define AT91_SHDW_WKUPIS(x)     ((1 << (x)) << AT91_SHDW_WKUPIS_SHIFT \
                                                & AT91_SHDW_WKUPIS_MASK)

#define AT91_SHDW_WUIR  0x0c            /* Shutdown Wake-up Inputs Register */
#define AT91_SHDW_WKUPEN_MASK   GENMASK(15, 0)
#define AT91_SHDW_WKUPEN(x)     ((1 << (x)) & AT91_SHDW_WKUPEN_MASK)
#define AT91_SHDW_WKUPT_SHIFT   16
#define AT91_SHDW_WKUPT_MASK    GENMASK(31, 16)
#define AT91_SHDW_WKUPT(x)      ((1 << (x)) << AT91_SHDW_WKUPT_SHIFT \
                                                & AT91_SHDW_WKUPT_MASK)

#define SHDW_WK_PIN(reg, cfg)   ((reg) & AT91_SHDW_WKUPIS((cfg)->wkup_pin_input))
#define SHDW_RTCWK(reg, cfg)    (((reg) >> ((cfg)->sr_rtcwk_shift)) & 0x1)
#define SHDW_RTTWK(reg, cfg)    (((reg) >> ((cfg)->sr_rttwk_shift)) & 0x1)
#define SHDW_RTCWKEN(cfg)       (1 << ((cfg)->mr_rtcwk_shift))
#define SHDW_RTTWKEN(cfg)       (1 << ((cfg)->mr_rttwk_shift))

#define DBC_PERIOD_US(x)        DIV_ROUND_UP_ULL((1000000 * (x)), \
                                                        SLOW_CLOCK_FREQ)

#define SHDW_CFG_NOT_USED       (32)

struct shdwc_reg_config {
        u8 wkup_pin_input;
        u8 mr_rtcwk_shift;
        u8 mr_rttwk_shift;
        u8 sr_rtcwk_shift;
        u8 sr_rttwk_shift;
};

struct pmc_reg_config {
        u8 mckr;
};

struct ddrc_reg_config {
        u32 type_offset;
        u32 type_mask;
};

struct reg_config {
        struct shdwc_reg_config shdwc;
        struct pmc_reg_config pmc;
        struct ddrc_reg_config ddrc;
};

struct shdwc {
        const struct reg_config *rcfg;
        struct clk *sclk;
        void __iomem *shdwc_base;
        void __iomem *mpddrc_base;
        void __iomem *pmc_base;
};

/*
 * Hold configuration here, cannot be more than one instance of the driver
 * since pm_power_off itself is global.
 */
static struct shdwc *at91_shdwc;

static const unsigned long long sdwc_dbc_period[] = {
        0, 3, 32, 512, 4096, 32768,
};

static void at91_wakeup_status(struct platform_device *pdev)
{
        struct shdwc *shdw = platform_get_drvdata(pdev);
        const struct reg_config *rcfg = shdw->rcfg;
        u32 reg;
        char *reason = "unknown";

        reg = readl(shdw->shdwc_base + AT91_SHDW_SR);

        dev_dbg(&pdev->dev, "%s: status = %#x\n", __func__, reg);

        /* Simple power-on, just bail out */
        if (!reg)
                return;

        if (SHDW_WK_PIN(reg, &rcfg->shdwc))
                reason = "WKUP pin";
        else if (SHDW_RTCWK(reg, &rcfg->shdwc))
                reason = "RTC";
        else if (SHDW_RTTWK(reg, &rcfg->shdwc))
                reason = "RTT";

        dev_info(&pdev->dev, "Wake-Up source: %s\n", reason);
}

static void at91_poweroff(void)
{
        asm volatile(
                /* Align to cache lines */
                ".balign 32\n\t"

                /* Ensure AT91_SHDW_CR is in the TLB by reading it */
                "       ldr     r6, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"

                /* Power down SDRAM0 */
                "       tst     %0, #0\n\t"
                "       beq     1f\n\t"
                "       str     %1, [%0, #" __stringify(AT91_DDRSDRC_LPR) "]\n\t"

                /* Switch the master clock source to slow clock. */
                "1:     ldr     r6, [%4, %5]\n\t"
                "       bic     r6, r6,  #" __stringify(AT91_PMC_CSS) "\n\t"
                "       str     r6, [%4, %5]\n\t"
                /* Wait for clock switch. */
                "2:     ldr     r6, [%4, #" __stringify(AT91_PMC_SR) "]\n\t"
                "       tst     r6, #"      __stringify(AT91_PMC_MCKRDY) "\n\t"
                "       beq     2b\n\t"

                /* Shutdown CPU */
                "       str     %3, [%2, #" __stringify(AT91_SHDW_CR) "]\n\t"

                "       b       .\n\t"
                :
                : "r" (at91_shdwc->mpddrc_base),
                  "r" cpu_to_le32(AT91_DDRSDRC_LPDDR2_PWOFF),
                  "r" (at91_shdwc->shdwc_base),
                  "r" cpu_to_le32(AT91_SHDW_KEY | AT91_SHDW_SHDW),
                  "r" (at91_shdwc->pmc_base),
                  "r" (at91_shdwc->rcfg->pmc.mckr)
                : "r6");
}

static u32 at91_shdwc_debouncer_value(struct platform_device *pdev,
                                      u32 in_period_us)
{
        int i;
        int max_idx = ARRAY_SIZE(sdwc_dbc_period) - 1;
        unsigned long long period_us;
        unsigned long long max_period_us = DBC_PERIOD_US(sdwc_dbc_period[max_idx]);

        if (in_period_us > max_period_us) {
                dev_warn(&pdev->dev,
                         "debouncer period %u too big, reduced to %llu us\n",
                         in_period_us, max_period_us);
                return max_idx;
        }

        for (i = max_idx - 1; i > 0; i--) {
                period_us = DBC_PERIOD_US(sdwc_dbc_period[i]);
                dev_dbg(&pdev->dev, "%s: ref[%d] = %llu\n",
                                                __func__, i, period_us);
                if (in_period_us > period_us)
                        break;
        }

        return i + 1;
}

static u32 at91_shdwc_get_wakeup_input(struct platform_device *pdev,
                                       struct device_node *np)
{
        struct device_node *cnp;
        u32 wk_input_mask;
        u32 wuir = 0;
        u32 wk_input;

        for_each_child_of_node(np, cnp) {
                if (of_property_read_u32(cnp, "reg", &wk_input)) {
                        dev_warn(&pdev->dev, "reg property is missing for %pOF\n",
                                 cnp);
                        continue;
                }

                wk_input_mask = 1 << wk_input;
                if (!(wk_input_mask & AT91_SHDW_WKUPEN_MASK)) {
                        dev_warn(&pdev->dev,
                                 "wake-up input %d out of bounds ignore\n",
                                 wk_input);
                        continue;
                }
                wuir |= wk_input_mask;

                if (of_property_read_bool(cnp, "atmel,wakeup-active-high"))
                        wuir |= AT91_SHDW_WKUPT(wk_input);

                dev_dbg(&pdev->dev, "%s: (child %d) wuir = %#x\n",
                                                __func__, wk_input, wuir);
        }

        return wuir;
}

static void at91_shdwc_dt_configure(struct platform_device *pdev)
{
        struct shdwc *shdw = platform_get_drvdata(pdev);
        const struct reg_config *rcfg = shdw->rcfg;
        struct device_node *np = pdev->dev.of_node;
        u32 mode = 0, tmp, input;

        if (!np) {
                dev_err(&pdev->dev, "device node not found\n");
                return;
        }

        if (!of_property_read_u32(np, "debounce-delay-us", &tmp))
                mode |= AT91_SHDW_WKUPDBC(at91_shdwc_debouncer_value(pdev, tmp));

        if (of_property_read_bool(np, "atmel,wakeup-rtc-timer"))
                mode |= SHDW_RTCWKEN(&rcfg->shdwc);

        if (of_property_read_bool(np, "atmel,wakeup-rtt-timer"))
                mode |= SHDW_RTTWKEN(&rcfg->shdwc);

        dev_dbg(&pdev->dev, "%s: mode = %#x\n", __func__, mode);
        writel(mode, shdw->shdwc_base + AT91_SHDW_MR);

        input = at91_shdwc_get_wakeup_input(pdev, np);
        writel(input, shdw->shdwc_base + AT91_SHDW_WUIR);
}

static const struct reg_config sama5d2_reg_config = {
        .shdwc = {
                .wkup_pin_input = 0,
                .mr_rtcwk_shift = 17,
                .mr_rttwk_shift = SHDW_CFG_NOT_USED,
                .sr_rtcwk_shift = 5,
                .sr_rttwk_shift = SHDW_CFG_NOT_USED,
        },
        .pmc = {
                .mckr           = 0x30,
        },
        .ddrc = {
                .type_offset    = AT91_DDRSDRC_MDR,
                .type_mask      = AT91_DDRSDRC_MD
        },
};

static const struct reg_config sam9x60_reg_config = {
        .shdwc = {
                .wkup_pin_input = 0,
                .mr_rtcwk_shift = 17,
                .mr_rttwk_shift = 16,
                .sr_rtcwk_shift = 5,
                .sr_rttwk_shift = 4,
        },
        .pmc = {
                .mckr           = 0x28,
        },
        .ddrc = {
                .type_offset    = AT91_DDRSDRC_MDR,
                .type_mask      = AT91_DDRSDRC_MD
        },
};

static const struct reg_config sama7g5_reg_config = {
        .shdwc = {
                .wkup_pin_input = 0,
                .mr_rtcwk_shift = 17,
                .mr_rttwk_shift = 16,
                .sr_rtcwk_shift = 5,
                .sr_rttwk_shift = 4,
        },
        .pmc = {
                .mckr           = 0x28,
        },
};

static const struct of_device_id at91_shdwc_of_match[] = {
        {
                .compatible = "atmel,sama5d2-shdwc",
                .data = &sama5d2_reg_config,
        },
        {
                .compatible = "microchip,sam9x60-shdwc",
                .data = &sam9x60_reg_config,
        },
        {
                .compatible = "microchip,sama7g5-shdwc",
                .data = &sama7g5_reg_config,
        }, {
                /*sentinel*/
        }
};
MODULE_DEVICE_TABLE(of, at91_shdwc_of_match);

static const struct of_device_id at91_pmc_ids[] = {
        { .compatible = "atmel,sama5d2-pmc" },
        { .compatible = "microchip,sam9x60-pmc" },
        { .compatible = "microchip,sama7g5-pmc" },
        { .compatible = "microchip,sam9x7-pmc" },
        { .compatible = "microchip,sama7d65-pmc" },
        { /* Sentinel. */ }
};

static int at91_shdwc_probe(struct platform_device *pdev)
{
        const struct of_device_id *match;
        struct device_node *np;
        u32 ddr_type;
        int ret;

        if (!pdev->dev.of_node)
                return -ENODEV;

        if (at91_shdwc)
                return -EBUSY;

        at91_shdwc = devm_kzalloc(&pdev->dev, sizeof(*at91_shdwc), GFP_KERNEL);
        if (!at91_shdwc)
                return -ENOMEM;

        platform_set_drvdata(pdev, at91_shdwc);

        at91_shdwc->shdwc_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(at91_shdwc->shdwc_base))
                return PTR_ERR(at91_shdwc->shdwc_base);

        match = of_match_node(at91_shdwc_of_match, pdev->dev.of_node);
        at91_shdwc->rcfg = match->data;

        at91_shdwc->sclk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(at91_shdwc->sclk))
                return PTR_ERR(at91_shdwc->sclk);

        ret = clk_prepare_enable(at91_shdwc->sclk);
        if (ret) {
                dev_err(&pdev->dev, "Could not enable slow clock\n");
                return ret;
        }

        at91_wakeup_status(pdev);

        at91_shdwc_dt_configure(pdev);

        np = of_find_matching_node(NULL, at91_pmc_ids);
        if (!np) {
                ret = -ENODEV;
                goto clk_disable;
        }

        at91_shdwc->pmc_base = of_iomap(np, 0);
        of_node_put(np);

        if (!at91_shdwc->pmc_base) {
                ret = -ENOMEM;
                goto clk_disable;
        }

        if (at91_shdwc->rcfg->ddrc.type_mask) {
                np = of_find_compatible_node(NULL, NULL,
                                             "atmel,sama5d3-ddramc");
                if (!np) {
                        ret = -ENODEV;
                        goto unmap;
                }

                at91_shdwc->mpddrc_base = of_iomap(np, 0);
                of_node_put(np);

                if (!at91_shdwc->mpddrc_base) {
                        ret = -ENOMEM;
                        goto unmap;
                }

                ddr_type = readl(at91_shdwc->mpddrc_base +
                                 at91_shdwc->rcfg->ddrc.type_offset) &
                                 at91_shdwc->rcfg->ddrc.type_mask;
                if (ddr_type != AT91_DDRSDRC_MD_LPDDR2 &&
                    ddr_type != AT91_DDRSDRC_MD_LPDDR3) {
                        iounmap(at91_shdwc->mpddrc_base);
                        at91_shdwc->mpddrc_base = NULL;
                }
        }

        pm_power_off = at91_poweroff;

        return 0;

unmap:
        iounmap(at91_shdwc->pmc_base);
clk_disable:
        clk_disable_unprepare(at91_shdwc->sclk);

        return ret;
}

static void at91_shdwc_remove(struct platform_device *pdev)
{
        struct shdwc *shdw = platform_get_drvdata(pdev);

        if (pm_power_off == at91_poweroff)
                pm_power_off = NULL;

        /* Reset values to disable wake-up features  */
        writel(0, shdw->shdwc_base + AT91_SHDW_MR);
        writel(0, shdw->shdwc_base + AT91_SHDW_WUIR);

        if (shdw->mpddrc_base)
                iounmap(shdw->mpddrc_base);
        iounmap(shdw->pmc_base);

        clk_disable_unprepare(shdw->sclk);
}

static struct platform_driver at91_shdwc_driver = {
        .probe = at91_shdwc_probe,
        .remove = at91_shdwc_remove,
        .driver = {
                .name = "at91-shdwc",
                .of_match_table = at91_shdwc_of_match,
        },
};
module_platform_driver(at91_shdwc_driver);

MODULE_AUTHOR("Nicolas Ferre <nicolas.ferre@atmel.com>");
MODULE_DESCRIPTION("Atmel shutdown controller driver");
MODULE_LICENSE("GPL v2");