// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * DaVinci DA850 AHCI SATA platform driver
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pm.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/libata.h>
#include <linux/ahci_platform.h>
#include "ahci.h"

#define DRV_NAME                "ahci_da850"
#define HARDRESET_RETRIES       5

/* SATA PHY Control Register offset from AHCI base */
#define SATA_P0PHYCR_REG        0x178

#define SATA_PHY_MPY(x)         ((x) << 0)
#define SATA_PHY_LOS(x)         ((x) << 6)
#define SATA_PHY_RXCDR(x)       ((x) << 10)
#define SATA_PHY_RXEQ(x)        ((x) << 13)
#define SATA_PHY_TXSWING(x)     ((x) << 19)
#define SATA_PHY_ENPLL(x)       ((x) << 31)

static void da850_sata_init(struct device *dev, void __iomem *pwrdn_reg,
                            void __iomem *ahci_base, u32 mpy)
{
        unsigned int val;

        /* Enable SATA clock receiver */
        val = readl(pwrdn_reg);
        val &= ~BIT(0);
        writel(val, pwrdn_reg);

        val = SATA_PHY_MPY(mpy) | SATA_PHY_LOS(1) | SATA_PHY_RXCDR(4) |
              SATA_PHY_RXEQ(1) | SATA_PHY_TXSWING(3) | SATA_PHY_ENPLL(1);

        writel(val, ahci_base + SATA_P0PHYCR_REG);
}

static u32 ahci_da850_calculate_mpy(unsigned long refclk_rate)
{
        u32 pll_output = 1500000000, needed;

        /*
         * We need to determine the value of the multiplier (MPY) bits.
         * In order to include the 12.5 multiplier we need to first divide
         * the refclk rate by ten.
         *
         * __div64_32() turned out to be unreliable, sometimes returning
         * false results.
         */
        WARN((refclk_rate % 10) != 0, "refclk must be divisible by 10");
        needed = pll_output / (refclk_rate / 10);

        /*
         * What we have now is (multiplier * 10).
         *
         * Let's determine the actual register value we need to write.
         */

        switch (needed) {
        case 50:
                return 0x1;
        case 60:
                return 0x2;
        case 80:
                return 0x4;
        case 100:
                return 0x5;
        case 120:
                return 0x6;
        case 125:
                return 0x7;
        case 150:
                return 0x8;
        case 200:
                return 0x9;
        case 250:
                return 0xa;
        default:
                /*
                 * We should have divided evenly - if not, return an invalid
                 * value.
                 */
                return 0;
        }
}

static int ahci_da850_softreset(struct ata_link *link,
                                unsigned int *class, unsigned long deadline)
{
        int pmp, ret;

        pmp = sata_srst_pmp(link);

        /*
         * There's an issue with the SATA controller on da850 SoCs: if we
         * enable Port Multiplier support, but the drive is connected directly
         * to the board, it can't be detected. As a workaround: if PMP is
         * enabled, we first call ahci_do_softreset() and pass it the result of
         * sata_srst_pmp(). If this call fails, we retry with pmp = 0.
         */
        ret = ahci_do_softreset(link, class, pmp, deadline, ahci_check_ready);
        if (pmp && ret == -EBUSY)
                return ahci_do_softreset(link, class, 0,
                                         deadline, ahci_check_ready);

        return ret;
}

static int ahci_da850_hardreset(struct ata_link *link,
                                unsigned int *class, unsigned long deadline)
{
        int ret, retry = HARDRESET_RETRIES;
        bool online;

        /*
         * In order to correctly service the LCD controller of the da850 SoC,
         * we increased the PLL0 frequency to 456MHz from the default 300MHz.
         *
         * This made the SATA controller unstable and the hardreset operation
         * does not always succeed the first time. Before really giving up to
         * bring up the link, retry the reset a couple times.
         */
        do {
                ret = ahci_do_hardreset(link, class, deadline, &online);
                if (online)
                        return ret;
        } while (retry--);

        return ret;
}

static struct ata_port_operations ahci_da850_port_ops = {
        .inherits = &ahci_platform_ops,
        .softreset = ahci_da850_softreset,
        /*
         * No need to override .pmp_softreset - it's only used for actual
         * PMP-enabled ports.
         */
        .hardreset = ahci_da850_hardreset,
        .pmp_hardreset = ahci_da850_hardreset,
};

static const struct ata_port_info ahci_da850_port_info = {
        .flags          = AHCI_FLAG_COMMON,
        .pio_mask       = ATA_PIO4,
        .udma_mask      = ATA_UDMA6,
        .port_ops       = &ahci_da850_port_ops,
};

static struct scsi_host_template ahci_platform_sht = {
        AHCI_SHT(DRV_NAME),
};

static int ahci_da850_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct ahci_host_priv *hpriv;
        void __iomem *pwrdn_reg;
        struct resource *res;
        struct clk *clk;
        u32 mpy;
        int rc;

        hpriv = ahci_platform_get_resources(pdev, 0);
        if (IS_ERR(hpriv))
                return PTR_ERR(hpriv);

        /*
         * Internally ahci_platform_get_resources() calls clk_get(dev, NULL)
         * when trying to obtain the functional clock. This SATA controller
         * uses two clocks for which we specify two connection ids. If we don't
         * have the functional clock at this point - call clk_get() again with
         * con_id = "fck".
         */
        if (!hpriv->clks[0]) {
                clk = clk_get(dev, "fck");
                if (IS_ERR(clk))
                        return PTR_ERR(clk);

                hpriv->clks[0] = clk;
        }

        /*
         * The second clock used by ahci-da850 is the external REFCLK. If we
         * didn't get it from ahci_platform_get_resources(), let's try to
         * specify the con_id in clk_get().
         */
        if (!hpriv->clks[1]) {
                clk = clk_get(dev, "refclk");
                if (IS_ERR(clk)) {
                        dev_err(dev, "unable to obtain the reference clock");
                        return -ENODEV;
                }

                hpriv->clks[1] = clk;
        }

        mpy = ahci_da850_calculate_mpy(clk_get_rate(hpriv->clks[1]));
        if (mpy == 0) {
                dev_err(dev, "invalid REFCLK multiplier value: 0x%x", mpy);
                return -EINVAL;
        }

        rc = ahci_platform_enable_resources(hpriv);
        if (rc)
                return rc;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!res) {
                rc = -ENODEV;
                goto disable_resources;
        }

        pwrdn_reg = devm_ioremap(dev, res->start, resource_size(res));
        if (!pwrdn_reg) {
                rc = -ENOMEM;
                goto disable_resources;
        }

        da850_sata_init(dev, pwrdn_reg, hpriv->mmio, mpy);

        rc = ahci_platform_init_host(pdev, hpriv, &ahci_da850_port_info,
                                     &ahci_platform_sht);
        if (rc)
                goto disable_resources;

        return 0;
disable_resources:
        ahci_platform_disable_resources(hpriv);
        return rc;
}

static SIMPLE_DEV_PM_OPS(ahci_da850_pm_ops, ahci_platform_suspend,
                         ahci_platform_resume);

static const struct of_device_id ahci_da850_of_match[] = {
        { .compatible = "ti,da850-ahci", },
        { },
};
MODULE_DEVICE_TABLE(of, ahci_da850_of_match);

static struct platform_driver ahci_da850_driver = {
        .probe = ahci_da850_probe,
        .remove = ata_platform_remove_one,
        .driver = {
                .name = DRV_NAME,
                .of_match_table = ahci_da850_of_match,
                .pm = &ahci_da850_pm_ops,
        },
};
module_platform_driver(ahci_da850_driver);

MODULE_DESCRIPTION("DaVinci DA850 AHCI SATA platform driver");
MODULE_AUTHOR("Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>");
MODULE_LICENSE("GPL");