// SPDX-License-Identifier: GPL-2.0
/*
 * Flex Timer Module Quadrature decoder
 *
 * This module implements a driver for decoding the FTM quadrature
 * of ex. a LS1021A
 */

#include <linux/fsl/ftm.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/io.h>
#include <linux/mutex.h>
#include <linux/counter.h>
#include <linux/bitfield.h>

#define FTM_FIELD_UPDATE(ftm, offset, mask, val)                        \
        ({                                                              \
                uint32_t flags;                                         \
                ftm_read(ftm, offset, &flags);                          \
                flags &= ~mask;                                         \
                flags |= FIELD_PREP(mask, val);                         \
                ftm_write(ftm, offset, flags);                          \
        })

struct ftm_quaddec {
        struct counter_device counter;
        struct platform_device *pdev;
        void __iomem *ftm_base;
        bool big_endian;
        struct mutex ftm_quaddec_mutex;
};

static void ftm_read(struct ftm_quaddec *ftm, uint32_t offset, uint32_t *data)
{
        if (ftm->big_endian)
                *data = ioread32be(ftm->ftm_base + offset);
        else
                *data = ioread32(ftm->ftm_base + offset);
}

static void ftm_write(struct ftm_quaddec *ftm, uint32_t offset, uint32_t data)
{
        if (ftm->big_endian)
                iowrite32be(data, ftm->ftm_base + offset);
        else
                iowrite32(data, ftm->ftm_base + offset);
}

/* Hold mutex before modifying write protection state */
static void ftm_clear_write_protection(struct ftm_quaddec *ftm)
{
        uint32_t flag;

        /* First see if it is enabled */
        ftm_read(ftm, FTM_FMS, &flag);

        if (flag & FTM_FMS_WPEN)
                FTM_FIELD_UPDATE(ftm, FTM_MODE, FTM_MODE_WPDIS, 1);
}

static void ftm_set_write_protection(struct ftm_quaddec *ftm)
{
        FTM_FIELD_UPDATE(ftm, FTM_FMS, FTM_FMS_WPEN, 1);
}

static void ftm_reset_counter(struct ftm_quaddec *ftm)
{
        /* Reset hardware counter to CNTIN */
        ftm_write(ftm, FTM_CNT, 0x0);
}

static void ftm_quaddec_init(struct ftm_quaddec *ftm)
{
        ftm_clear_write_protection(ftm);

        /*
         * Do not write in the region from the CNTIN register through the
         * PWMLOAD register when FTMEN = 0.
         * Also reset other fields to zero
         */
        ftm_write(ftm, FTM_MODE, FTM_MODE_FTMEN);
        ftm_write(ftm, FTM_CNTIN, 0x0000);
        ftm_write(ftm, FTM_MOD, 0xffff);
        ftm_write(ftm, FTM_CNT, 0x0);
        /* Set prescaler, reset other fields to zero */
        ftm_write(ftm, FTM_SC, FTM_SC_PS_1);

        /* Select quad mode, reset other fields to zero */
        ftm_write(ftm, FTM_QDCTRL, FTM_QDCTRL_QUADEN);

        /* Unused features and reset to default section */
        ftm_write(ftm, FTM_POL, 0x0);
        ftm_write(ftm, FTM_FLTCTRL, 0x0);
        ftm_write(ftm, FTM_SYNCONF, 0x0);
        ftm_write(ftm, FTM_SYNC, 0xffff);

        /* Lock the FTM */
        ftm_set_write_protection(ftm);
}

static void ftm_quaddec_disable(void *ftm)
{
        struct ftm_quaddec *ftm_qua = ftm;

        ftm_clear_write_protection(ftm_qua);
        ftm_write(ftm_qua, FTM_MODE, 0);
        ftm_write(ftm_qua, FTM_QDCTRL, 0);
        /*
         * This is enough to disable the counter. No clock has been
         * selected by writing to FTM_SC in init()
         */
        ftm_set_write_protection(ftm_qua);
}

static int ftm_quaddec_get_prescaler(struct counter_device *counter,
                                     struct counter_count *count,
                                     size_t *cnt_mode)
{
        struct ftm_quaddec *ftm = counter->priv;
        uint32_t scflags;

        ftm_read(ftm, FTM_SC, &scflags);

        *cnt_mode = FIELD_GET(FTM_SC_PS_MASK, scflags);

        return 0;
}

static int ftm_quaddec_set_prescaler(struct counter_device *counter,
                                     struct counter_count *count,
                                     size_t cnt_mode)
{
        struct ftm_quaddec *ftm = counter->priv;

        mutex_lock(&ftm->ftm_quaddec_mutex);

        ftm_clear_write_protection(ftm);
        FTM_FIELD_UPDATE(ftm, FTM_SC, FTM_SC_PS_MASK, cnt_mode);
        ftm_set_write_protection(ftm);

        /* Also resets the counter as it is undefined anyway now */
        ftm_reset_counter(ftm);

        mutex_unlock(&ftm->ftm_quaddec_mutex);
        return 0;
}

static const char * const ftm_quaddec_prescaler[] = {
        "1", "2", "4", "8", "16", "32", "64", "128"
};

static struct counter_count_enum_ext ftm_quaddec_prescaler_enum = {
        .items = ftm_quaddec_prescaler,
        .num_items = ARRAY_SIZE(ftm_quaddec_prescaler),
        .get = ftm_quaddec_get_prescaler,
        .set = ftm_quaddec_set_prescaler
};

enum ftm_quaddec_synapse_action {
        FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES,
};

static enum counter_synapse_action ftm_quaddec_synapse_actions[] = {
        [FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES] =
        COUNTER_SYNAPSE_ACTION_BOTH_EDGES
};

enum ftm_quaddec_count_function {
        FTM_QUADDEC_COUNT_ENCODER_MODE_1,
};

static const enum counter_count_function ftm_quaddec_count_functions[] = {
        [FTM_QUADDEC_COUNT_ENCODER_MODE_1] =
        COUNTER_COUNT_FUNCTION_QUADRATURE_X4
};

static int ftm_quaddec_count_read(struct counter_device *counter,
                                  struct counter_count *count,
                                  struct counter_count_read_value *val)
{
        struct ftm_quaddec *const ftm = counter->priv;
        uint32_t cntval;

        ftm_read(ftm, FTM_CNT, &cntval);

        counter_count_read_value_set(val, COUNTER_COUNT_POSITION, &cntval);

        return 0;
}

static int ftm_quaddec_count_write(struct counter_device *counter,
                                   struct counter_count *count,
                                   struct counter_count_write_value *val)
{
        struct ftm_quaddec *const ftm = counter->priv;
        u32 cnt;
        int err;

        err = counter_count_write_value_get(&cnt, COUNTER_COUNT_POSITION, val);
        if (err)
                return err;

        if (cnt != 0) {
                dev_warn(&ftm->pdev->dev, "Can only accept '0' as new counter value\n");
                return -EINVAL;
        }

        ftm_reset_counter(ftm);

        return 0;
}

static int ftm_quaddec_count_function_get(struct counter_device *counter,
                                          struct counter_count *count,
                                          size_t *function)
{
        *function = FTM_QUADDEC_COUNT_ENCODER_MODE_1;

        return 0;
}

static int ftm_quaddec_action_get(struct counter_device *counter,
                                  struct counter_count *count,
                                  struct counter_synapse *synapse,
                                  size_t *action)
{
        *action = FTM_QUADDEC_SYNAPSE_ACTION_BOTH_EDGES;

        return 0;
}

static const struct counter_ops ftm_quaddec_cnt_ops = {
        .count_read = ftm_quaddec_count_read,
        .count_write = ftm_quaddec_count_write,
        .function_get = ftm_quaddec_count_function_get,
        .action_get = ftm_quaddec_action_get,
};

static struct counter_signal ftm_quaddec_signals[] = {
        {
                .id = 0,
                .name = "Channel 1 Phase A"
        },
        {
                .id = 1,
                .name = "Channel 1 Phase B"
        }
};

static struct counter_synapse ftm_quaddec_count_synapses[] = {
        {
                .actions_list = ftm_quaddec_synapse_actions,
                .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
                .signal = &ftm_quaddec_signals[0]
        },
        {
                .actions_list = ftm_quaddec_synapse_actions,
                .num_actions = ARRAY_SIZE(ftm_quaddec_synapse_actions),
                .signal = &ftm_quaddec_signals[1]
        }
};

static const struct counter_count_ext ftm_quaddec_count_ext[] = {
        COUNTER_COUNT_ENUM("prescaler", &ftm_quaddec_prescaler_enum),
        COUNTER_COUNT_ENUM_AVAILABLE("prescaler", &ftm_quaddec_prescaler_enum),
};

static struct counter_count ftm_quaddec_counts = {
        .id = 0,
        .name = "Channel 1 Count",
        .functions_list = ftm_quaddec_count_functions,
        .num_functions = ARRAY_SIZE(ftm_quaddec_count_functions),
        .synapses = ftm_quaddec_count_synapses,
        .num_synapses = ARRAY_SIZE(ftm_quaddec_count_synapses),
        .ext = ftm_quaddec_count_ext,
        .num_ext = ARRAY_SIZE(ftm_quaddec_count_ext)
};

static int ftm_quaddec_probe(struct platform_device *pdev)
{
        struct ftm_quaddec *ftm;

        struct device_node *node = pdev->dev.of_node;
        struct resource *io;
        int ret;

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

        platform_set_drvdata(pdev, ftm);

        io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!io) {
                dev_err(&pdev->dev, "Failed to get memory region\n");
                return -ENODEV;
        }

        ftm->pdev = pdev;
        ftm->big_endian = of_property_read_bool(node, "big-endian");
        ftm->ftm_base = devm_ioremap(&pdev->dev, io->start, resource_size(io));

        if (!ftm->ftm_base) {
                dev_err(&pdev->dev, "Failed to map memory region\n");
                return -EINVAL;
        }
        ftm->counter.name = dev_name(&pdev->dev);
        ftm->counter.parent = &pdev->dev;
        ftm->counter.ops = &ftm_quaddec_cnt_ops;
        ftm->counter.counts = &ftm_quaddec_counts;
        ftm->counter.num_counts = 1;
        ftm->counter.signals = ftm_quaddec_signals;
        ftm->counter.num_signals = ARRAY_SIZE(ftm_quaddec_signals);
        ftm->counter.priv = ftm;

        mutex_init(&ftm->ftm_quaddec_mutex);

        ftm_quaddec_init(ftm);

        ret = devm_add_action_or_reset(&pdev->dev, ftm_quaddec_disable, ftm);
        if (ret)
                return ret;

        ret = devm_counter_register(&pdev->dev, &ftm->counter);
        if (ret)
                return ret;

        return 0;
}

static const struct of_device_id ftm_quaddec_match[] = {
        { .compatible = "fsl,ftm-quaddec" },
        {},
};

static struct platform_driver ftm_quaddec_driver = {
        .driver = {
                .name = "ftm-quaddec",
                .of_match_table = ftm_quaddec_match,
        },
        .probe = ftm_quaddec_probe,
};

module_platform_driver(ftm_quaddec_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Kjeld Flarup <kfa@deif.com>");
MODULE_AUTHOR("Patrick Havelange <patrick.havelange@essensium.com>");