// SPDX-License-Identifier: GPL-2.0-only
/*
 * TI AEMIF driver
 *
 * Copyright (C) 2010 - 2013 Texas Instruments Incorporated. http://www.ti.com/
 *
 * Authors:
 * Murali Karicheri <m-karicheri2@ti.com>
 * Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
 */

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/memory/ti-aemif.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>

#define TA_SHIFT        2
#define RHOLD_SHIFT     4
#define RSTROBE_SHIFT   7
#define RSETUP_SHIFT    13
#define WHOLD_SHIFT     17
#define WSTROBE_SHIFT   20
#define WSETUP_SHIFT    26
#define EW_SHIFT        30
#define SSTROBE_SHIFT   31

#define TA(x)           ((x) << TA_SHIFT)
#define RHOLD(x)        ((x) << RHOLD_SHIFT)
#define RSTROBE(x)      ((x) << RSTROBE_SHIFT)
#define RSETUP(x)       ((x) << RSETUP_SHIFT)
#define WHOLD(x)        ((x) << WHOLD_SHIFT)
#define WSTROBE(x)      ((x) << WSTROBE_SHIFT)
#define WSETUP(x)       ((x) << WSETUP_SHIFT)
#define EW(x)           ((x) << EW_SHIFT)
#define SSTROBE(x)      ((x) << SSTROBE_SHIFT)

#define ASIZE_MAX       0x1
#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 EW_MAX          0x1
#define SSTROBE_MAX     0x1
#define NUM_CS          4

#define TA_VAL(x)       (((x) & TA(TA_MAX)) >> TA_SHIFT)
#define RHOLD_VAL(x)    (((x) & RHOLD(RHOLD_MAX)) >> RHOLD_SHIFT)
#define RSTROBE_VAL(x)  (((x) & RSTROBE(RSTROBE_MAX)) >> RSTROBE_SHIFT)
#define RSETUP_VAL(x)   (((x) & RSETUP(RSETUP_MAX)) >> RSETUP_SHIFT)
#define WHOLD_VAL(x)    (((x) & WHOLD(WHOLD_MAX)) >> WHOLD_SHIFT)
#define WSTROBE_VAL(x)  (((x) & WSTROBE(WSTROBE_MAX)) >> WSTROBE_SHIFT)
#define WSETUP_VAL(x)   (((x) & WSETUP(WSETUP_MAX)) >> WSETUP_SHIFT)
#define EW_VAL(x)       (((x) & EW(EW_MAX)) >> EW_SHIFT)
#define SSTROBE_VAL(x)  (((x) & SSTROBE(SSTROBE_MAX)) >> SSTROBE_SHIFT)

#define NRCSR_OFFSET    0x00
#define AWCCR_OFFSET    0x04
#define A1CR_OFFSET     0x10

#define ACR_ASIZE_MASK  0x3
#define ACR_EW_MASK     BIT(30)
#define ACR_SSTROBE_MASK        BIT(31)
#define ASIZE_16BIT     1

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

#define CONFIG_MASK     (EW(EW_MAX) | SSTROBE(SSTROBE_MAX) | ASIZE_MAX)

/**
 * struct aemif_cs_data: structure to hold CS parameters
 * @timings: timings configuration
 * @cs: chip-select number
 * @enable_ss: enable/disable select strobe mode
 * @enable_ew: enable/disable extended wait mode
 * @asize: width of the asynchronous device's data bus
 */
struct aemif_cs_data {
        struct aemif_cs_timings timings;
        u8      cs;
        u8      enable_ss;
        u8      enable_ew;
        u8      asize;
};

/**
 * struct aemif_device: structure to hold device data
 * @base: base address of AEMIF registers
 * @clk: source clock
 * @clk_rate: clock's rate in kHz
 * @num_cs: number of assigned chip-selects
 * @cs_offset: start number of cs nodes
 * @cs_data: array of chip-select settings
 * @config_cs_lock: lock used to access CS configuration
 */
struct aemif_device {
        void __iomem *base;
        struct clk *clk;
        unsigned long clk_rate;
        u8 num_cs;
        int cs_offset;
        struct aemif_cs_data cs_data[NUM_CS];
        struct mutex config_cs_lock;
};

/**
 * aemif_check_cs_timings() - Check the validity of a CS timing configuration.
 * @timings: timings configuration
 *
 * @return: 0 if the timing configuration is valid, negative error number otherwise.
 */
int aemif_check_cs_timings(struct aemif_cs_timings *timings)
{
        if (timings->ta > TA_MAX)
                return -EINVAL;

        if (timings->rhold > RHOLD_MAX)
                return -EINVAL;

        if (timings->rstrobe > RSTROBE_MAX)
                return -EINVAL;

        if (timings->rsetup > RSETUP_MAX)
                return -EINVAL;

        if (timings->whold > WHOLD_MAX)
                return -EINVAL;

        if (timings->wstrobe > WSTROBE_MAX)
                return -EINVAL;

        if (timings->wsetup > WSETUP_MAX)
                return -EINVAL;

        return 0;
}
EXPORT_SYMBOL_GPL(aemif_check_cs_timings);

/**
 * aemif_set_cs_timings() - Set the timing configuration of a given chip select.
 * @aemif: aemif device to configure
 * @cs: index of the chip select to configure
 * @timings: timings configuration to set
 *
 * @return: 0 on success, else negative errno.
 */
int aemif_set_cs_timings(struct aemif_device *aemif, u8 cs,
                         struct aemif_cs_timings *timings)
{
        unsigned int offset;
        u32 val, set;
        int ret;

        if (!timings || !aemif)
                return -EINVAL;

        if (cs > aemif->num_cs)
                return -EINVAL;

        ret = aemif_check_cs_timings(timings);
        if (ret)
                return ret;

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

        offset = A1CR_OFFSET + cs * 4;

        mutex_lock(&aemif->config_cs_lock);
        val = readl(aemif->base + offset);
        val &= ~TIMINGS_MASK;
        val |= set;
        writel(val, aemif->base + offset);
        mutex_unlock(&aemif->config_cs_lock);

        return 0;
}
EXPORT_SYMBOL_GPL(aemif_set_cs_timings);

/**
 * aemif_calc_rate - calculate timing data.
 * @pdev: platform device to calculate for
 * @wanted: The cycle time needed in nanoseconds.
 * @clk: The input clock rate in kHz.
 *
 * @return: the calculated timing value minus 1 for easy
 * programming into AEMIF timing registers.
 */
static u32 aemif_calc_rate(struct platform_device *pdev, int wanted, unsigned long clk)
{
        int result;

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

        dev_dbg(&pdev->dev, "%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;

        return result;
}

/**
 * aemif_config_abus - configure async bus parameters
 * @pdev: platform device to configure for
 * @csnum: aemif chip select number
 *
 * 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 aemif_config_abus(struct platform_device *pdev, int csnum)
{
        struct aemif_device *aemif = platform_get_drvdata(pdev);
        struct aemif_cs_data *data = &aemif->cs_data[csnum];
        unsigned offset;
        u32 set, val;

        offset = A1CR_OFFSET + (data->cs - aemif->cs_offset) * 4;

        set = (data->asize & ACR_ASIZE_MASK);
        if (data->enable_ew)
                set |= ACR_EW_MASK;
        if (data->enable_ss)
                set |= ACR_SSTROBE_MASK;

        mutex_lock(&aemif->config_cs_lock);
        val = readl(aemif->base + offset);
        val &= ~CONFIG_MASK;
        val |= set;
        writel(val, aemif->base + offset);
        mutex_unlock(&aemif->config_cs_lock);

        return aemif_set_cs_timings(aemif, data->cs - aemif->cs_offset, &data->timings);
}

/**
 * aemif_get_hw_params - function to read hw register values
 * @pdev: platform device to read for
 * @csnum: aemif chip select number
 *
 * This function reads the defaults from the registers and update
 * the timing values. Required for get/set commands and also for
 * the case when driver needs to use defaults in hardware.
 */
static void aemif_get_hw_params(struct platform_device *pdev, int csnum)
{
        struct aemif_device *aemif = platform_get_drvdata(pdev);
        struct aemif_cs_data *data = &aemif->cs_data[csnum];
        u32 val, offset;

        offset = A1CR_OFFSET + (data->cs - aemif->cs_offset) * 4;
        val = readl(aemif->base + offset);

        data->timings.ta = TA_VAL(val);
        data->timings.rhold = RHOLD_VAL(val);
        data->timings.rstrobe = RSTROBE_VAL(val);
        data->timings.rsetup = RSETUP_VAL(val);
        data->timings.whold = WHOLD_VAL(val);
        data->timings.wstrobe = WSTROBE_VAL(val);
        data->timings.wsetup = WSETUP_VAL(val);
        data->enable_ew = EW_VAL(val);
        data->enable_ss = SSTROBE_VAL(val);
        data->asize = val & ASIZE_MAX;
}

/**
 * of_aemif_parse_abus_config - parse CS configuration from DT
 * @pdev: platform device to parse for
 * @np: device node ptr
 *
 * This function update the emif async bus configuration based on the values
 * configured in a cs device binding node.
 */
static int of_aemif_parse_abus_config(struct platform_device *pdev,
                                      struct device_node *np)
{
        struct aemif_device *aemif = platform_get_drvdata(pdev);
        unsigned long clk_rate = aemif->clk_rate;
        struct aemif_cs_data *data;
        u32 cs;
        u32 val;

        if (of_property_read_u32(np, "ti,cs-chipselect", &cs)) {
                dev_dbg(&pdev->dev, "cs property is required");
                return -EINVAL;
        }

        if (cs - aemif->cs_offset >= NUM_CS || cs < aemif->cs_offset) {
                dev_dbg(&pdev->dev, "cs number is incorrect %d", cs);
                return -EINVAL;
        }

        if (aemif->num_cs >= NUM_CS) {
                dev_dbg(&pdev->dev, "cs count is more than %d", NUM_CS);
                return -EINVAL;
        }

        data = &aemif->cs_data[aemif->num_cs];
        data->cs = cs;

        /* read the current value in the hw register */
        aemif_get_hw_params(pdev, aemif->num_cs++);

        /* override the values from device node */
        if (!of_property_read_u32(np, "ti,cs-min-turnaround-ns", &val))
                data->timings.ta = aemif_calc_rate(pdev, val, clk_rate);

        if (!of_property_read_u32(np, "ti,cs-read-hold-ns", &val))
                data->timings.rhold = aemif_calc_rate(pdev, val, clk_rate);

        if (!of_property_read_u32(np, "ti,cs-read-strobe-ns", &val))
                data->timings.rstrobe = aemif_calc_rate(pdev, val, clk_rate);

        if (!of_property_read_u32(np, "ti,cs-read-setup-ns", &val))
                data->timings.rsetup = aemif_calc_rate(pdev, val, clk_rate);

        if (!of_property_read_u32(np, "ti,cs-write-hold-ns", &val))
                data->timings.whold = aemif_calc_rate(pdev, val, clk_rate);

        if (!of_property_read_u32(np, "ti,cs-write-strobe-ns", &val))
                data->timings.wstrobe = aemif_calc_rate(pdev, val, clk_rate);

        if (!of_property_read_u32(np, "ti,cs-write-setup-ns", &val))
                data->timings.wsetup = aemif_calc_rate(pdev, val, clk_rate);

        if (!of_property_read_u32(np, "ti,cs-bus-width", &val))
                if (val == 16)
                        data->asize = 1;
        data->enable_ew = of_property_read_bool(np, "ti,cs-extended-wait-mode");
        data->enable_ss = of_property_read_bool(np, "ti,cs-select-strobe-mode");

        return aemif_check_cs_timings(&data->timings);
}

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

static int aemif_probe(struct platform_device *pdev)
{
        int i;
        int ret = -ENODEV;
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct aemif_device *aemif;

        aemif = devm_kzalloc(dev, sizeof(*aemif), GFP_KERNEL);
        if (!aemif)
                return -ENOMEM;

        platform_set_drvdata(pdev, aemif);

        aemif->clk = devm_clk_get_enabled(dev, NULL);
        if (IS_ERR(aemif->clk))
                return dev_err_probe(dev, PTR_ERR(aemif->clk),
                                     "cannot get clock 'aemif'\n");

        aemif->clk_rate = clk_get_rate(aemif->clk) / MSEC_PER_SEC;

        if (np && of_device_is_compatible(np, "ti,da850-aemif"))
                aemif->cs_offset = 2;

        aemif->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(aemif->base))
                return PTR_ERR(aemif->base);

        mutex_init(&aemif->config_cs_lock);
        if (np) {
                /*
                 * For every controller device node, there is a cs device node
                 * that describe the bus configuration parameters. This
                 * functions iterate over these nodes and update the cs data
                 * array.
                 */
                for_each_available_child_of_node_scoped(np, child_np) {
                        ret = of_aemif_parse_abus_config(pdev, child_np);
                        if (ret < 0)
                                return ret;
                }
        }

        for (i = 0; i < aemif->num_cs; i++) {
                ret = aemif_config_abus(pdev, i);
                if (ret < 0) {
                        dev_err(dev, "Error configuring chip select %d\n",
                                aemif->cs_data[i].cs);
                        return ret;
                }
        }

        /*
         * Create a child devices explicitly from here to guarantee that the
         * child will be probed after the AEMIF timing parameters are set.
         */
        if (np) {
                for_each_available_child_of_node_scoped(np, child_np) {
                        ret = of_platform_populate(child_np, NULL, NULL, dev);
                        if (ret < 0)
                                return ret;
                }
        }

        return 0;
}

static struct platform_driver aemif_driver = {
        .probe = aemif_probe,
        .driver = {
                .name = "ti-aemif",
                .of_match_table = of_match_ptr(aemif_of_match),
        },
};

module_platform_driver(aemif_driver);

MODULE_AUTHOR("Murali Karicheri <m-karicheri2@ti.com>");
MODULE_AUTHOR("Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>");
MODULE_DESCRIPTION("Texas Instruments AEMIF driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" KBUILD_MODNAME);