/*
 * AEMIF support for DaVinci SoCs
 *
 * Copyright (C) 2010 Texas Instruments Incorporated. http://www.ti.com/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/module.h>
#include <linux/time.h>

#include <linux/platform_data/mtd-davinci-aemif.h>
#include <linux/platform_data/mtd-davinci.h>

/* Timing value configuration */

#define TA(x)           ((x) << 2)
#define RHOLD(x)        ((x) << 4)
#define RSTROBE(x)      ((x) << 7)
#define RSETUP(x)       ((x) << 13)
#define WHOLD(x)        ((x) << 17)
#define WSTROBE(x)      ((x) << 20)
#define WSETUP(x)       ((x) << 26)

#define TA_MAX          0x3
#define RHOLD_MAX       0x7
#define RSTROBE_MAX     0x3f
#define RSETUP_MAX      0xf
#define WHOLD_MAX       0x7
#define WSTROBE_MAX     0x3f
#define WSETUP_MAX      0xf

#define TIMING_MASK     (TA(TA_MAX) | \
                                RHOLD(RHOLD_MAX) | \
                                RSTROBE(RSTROBE_MAX) |  \
                                RSETUP(RSETUP_MAX) | \
                                WHOLD(WHOLD_MAX) | \
                                WSTROBE(WSTROBE_MAX) | \
                                WSETUP(WSETUP_MAX))

static inline unsigned int davinci_aemif_readl(void __iomem *base, int offset)
{
        return readl_relaxed(base + offset);
}

static inline void davinci_aemif_writel(void __iomem *base,
                                        int offset, unsigned long value)
{
        writel_relaxed(value, base + offset);
}

/*
 * aemif_calc_rate - calculate timing data.
 * @wanted: The cycle time needed in nanoseconds.
 * @clk: The input clock rate in kHz.
 * @max: The maximum divider value that can be programmed.
 *
 * On success, returns the calculated timing value minus 1 for easy
 * programming into AEMIF timing registers, else negative errno.
 */
static int aemif_calc_rate(int wanted, unsigned long clk, int max)
{
        int result;

        result = DIV_ROUND_UP((wanted * clk), NSEC_PER_MSEC) - 1;

        pr_debug("%s: result %d from %ld, %d\n", __func__, result, clk, wanted);

        /* It is generally OK to have a more relaxed timing than requested... */
        if (result < 0)
                result = 0;

        /* ... But configuring tighter timings is not an option. */
        else if (result > max)
                result = -EINVAL;

        return result;
}

/**
 * davinci_aemif_setup_timing - setup timing values for a given AEMIF interface
 * @t: timing values to be progammed
 * @base: The virtual base address of the AEMIF interface
 * @cs: chip-select to program the timing values for
 * @clkrate: the AEMIF clkrate
 *
 * This function programs the given timing values (in real clock) into the
 * AEMIF registers taking the AEMIF clock into account.
 *
 * This function does not use any locking while programming the AEMIF
 * because it is expected that there is only one user of a given
 * chip-select.
 *
 * Returns 0 on success, else negative errno.
 */
static int davinci_aemif_setup_timing(struct davinci_aemif_timing *t,
                                        void __iomem *base, unsigned cs,
                                        unsigned long clkrate)
{
        unsigned set, val;
        int ta, rhold, rstrobe, rsetup, whold, wstrobe, wsetup;
        unsigned offset = A1CR_OFFSET + cs * 4;

        if (!t)
                return 0;       /* Nothing to do */

        clkrate /= 1000;        /* turn clock into kHz for ease of use */

        ta      = aemif_calc_rate(t->ta, clkrate, TA_MAX);
        rhold   = aemif_calc_rate(t->rhold, clkrate, RHOLD_MAX);
        rstrobe = aemif_calc_rate(t->rstrobe, clkrate, RSTROBE_MAX);
        rsetup  = aemif_calc_rate(t->rsetup, clkrate, RSETUP_MAX);
        whold   = aemif_calc_rate(t->whold, clkrate, WHOLD_MAX);
        wstrobe = aemif_calc_rate(t->wstrobe, clkrate, WSTROBE_MAX);
        wsetup  = aemif_calc_rate(t->wsetup, clkrate, WSETUP_MAX);

        if (ta < 0 || rhold < 0 || rstrobe < 0 || rsetup < 0 ||
                        whold < 0 || wstrobe < 0 || wsetup < 0) {
                pr_err("%s: cannot get suitable timings\n", __func__);
                return -EINVAL;
        }

        set = TA(ta) | RHOLD(rhold) | RSTROBE(rstrobe) | RSETUP(rsetup) |
                WHOLD(whold) | WSTROBE(wstrobe) | WSETUP(wsetup);

        val = __raw_readl(base + offset);
        val &= ~TIMING_MASK;
        val |= set;
        __raw_writel(val, base + offset);

        return 0;
}

/**
 * davinci_aemif_setup - setup AEMIF interface by davinci_nand_pdata
 * @pdev - link to platform device to setup settings for
 *
 * This function does not use any locking while programming the AEMIF
 * because it is expected that there is only one user of a given
 * chip-select.
 *
 * Returns 0 on success, else negative errno.
 */
int davinci_aemif_setup(struct platform_device *pdev)
{
        struct davinci_nand_pdata *pdata = dev_get_platdata(&pdev->dev);
        uint32_t val;
        unsigned long clkrate;
        struct resource *res;
        void __iomem *base;
        struct clk *clk;
        int ret = 0;

        clk = clk_get(&pdev->dev, "aemif");
        if (IS_ERR(clk)) {
                ret = PTR_ERR(clk);
                dev_dbg(&pdev->dev, "unable to get AEMIF clock, err %d\n", ret);
                return ret;
        }

        ret = clk_prepare_enable(clk);
        if (ret < 0) {
                dev_dbg(&pdev->dev, "unable to enable AEMIF clock, err %d\n",
                        ret);
                goto err_put;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!res) {
                dev_err(&pdev->dev, "cannot get IORESOURCE_MEM\n");
                ret = -ENOMEM;
                goto err;
        }

        base = ioremap(res->start, resource_size(res));
        if (!base) {
                dev_err(&pdev->dev, "ioremap failed for resource %pR\n", res);
                ret = -ENOMEM;
                goto err;
        }

        /*
         * Setup Async configuration register in case we did not boot
         * from NAND and so bootloader did not bother to set it up.
         */
        val = davinci_aemif_readl(base, A1CR_OFFSET + pdev->id * 4);
        /*
         * Extended Wait is not valid and Select Strobe mode is not
         * used
         */
        val &= ~(ACR_ASIZE_MASK | ACR_EW_MASK | ACR_SS_MASK);
        if (pdata->options & NAND_BUSWIDTH_16)
                val |= 0x1;

        davinci_aemif_writel(base, A1CR_OFFSET + pdev->id * 4, val);

        clkrate = clk_get_rate(clk);

        if (pdata->timing)
                ret = davinci_aemif_setup_timing(pdata->timing, base, pdev->id,
                                                 clkrate);

        if (ret < 0)
                dev_dbg(&pdev->dev, "NAND timing values setup fail\n");

        iounmap(base);
err:
        clk_disable_unprepare(clk);
err_put:
        clk_put(clk);
        return ret;
}