/*
 * Copyright (c) 2017, Linaro Ltd
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/mailbox_controller.h>
#include <linux/mfd/syscon.h>

#define QCOM_APCS_IPC_BITS	32

struct qcom_apcs_ipc {
	struct mbox_controller mbox;
	struct mbox_chan mbox_chans[QCOM_APCS_IPC_BITS];

	struct regmap *regmap;
	unsigned int offset;
	unsigned int bit;
	struct platform_device *clk;
};

static const struct regmap_config apcs_regmap_config = {
	.reg_bits = 32,
	.reg_stride = 4,
	.val_bits = 32,
	.max_register = 0x1000,
	.fast_io = true,
};

static int qcom_apcs_ipc_send_data(struct mbox_chan *chan, void *data)
{
	struct qcom_apcs_ipc *apcs = container_of(chan->mbox,
						  struct qcom_apcs_ipc, mbox);
	return regmap_write(apcs->regmap, apcs->offset, BIT(apcs->bit));
}

static const struct mbox_chan_ops qcom_apcs_ipc_ops = {
	.send_data = qcom_apcs_ipc_send_data,
};

static int qcom_apcs_ipc_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct qcom_apcs_ipc *apcs;
	unsigned long i;
	int ret;

	struct device_node *syscon;
	const char *key;

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

	syscon = of_parse_phandle(np, "qcom,ipc", 0);
	if (!syscon) {
		pr_err("no qcom,ipc node\n");
		return -ENODEV;
	}

	apcs->regmap = syscon_node_to_regmap(syscon);
	if (IS_ERR(apcs->regmap))
		return PTR_ERR(apcs->regmap);

	key = "qcom,ipc";
	ret = of_property_read_u32_index(np, key, 1, &apcs->offset);
	if (ret < 0) {
		pr_err("no offset in %s\n", key);
		return -EINVAL;
	}

	ret = of_property_read_u32_index(np, key, 2, &apcs->bit);
	if (ret < 0) {
		pr_err("no bit in %s\n", key);
		return -EINVAL;
	}


	/* Initialize channel identifiers */
	for (i = 0; i < ARRAY_SIZE(apcs->mbox_chans); i++)
		apcs->mbox_chans[i].con_priv = (void *)i;

	apcs->mbox.dev = &pdev->dev;
	apcs->mbox.ops = &qcom_apcs_ipc_ops;
	apcs->mbox.chans = apcs->mbox_chans;
	apcs->mbox.num_chans = ARRAY_SIZE(apcs->mbox_chans);

	ret = mbox_controller_register(&apcs->mbox);
	if (ret) {
		dev_err(&pdev->dev, "failed to register APCS IPC controller\n");
		return ret;
	}

	if (of_device_is_compatible(np, "qcom,msm8916-apcs-kpss-global")) {
		apcs->clk = platform_device_register_data(&pdev->dev,
							  "qcom-apcs-msm8916-clk",
							  -1, NULL, 0);
		if (IS_ERR(apcs->clk))
			dev_err(&pdev->dev, "failed to register APCS clk\n");
	}

	platform_set_drvdata(pdev, apcs);

	return 0;
}

static int qcom_apcs_ipc_remove(struct platform_device *pdev)
{
	struct qcom_apcs_ipc *apcs = platform_get_drvdata(pdev);
	struct platform_device *clk = apcs->clk;

	mbox_controller_unregister(&apcs->mbox);
	platform_device_unregister(clk);

	return 0;
}

/* .data is the offset of the ipc register within the global block */
static const struct of_device_id qcom_apcs_ipc_of_match[] = {
	{ .compatible = "qcom,msm8916-apcs-kpss-global", .data = (void *)8 },
	{ .compatible = "qcom,msm8996-apcs-hmss-global", .data = (void *)8 },
	{ .compatible = "qcom,msm8998-apcs-hmss-global", .data = (void *)8 },
	{ .compatible = "qcom,qcs404-apcs-apps-global", .data = (void *)8 },
	{ .compatible = "qcom,sdm845-apss-shared", .data = (void *)12 },
	{}
};
MODULE_DEVICE_TABLE(of, qcom_apcs_ipc_of_match);

static struct platform_driver qcom_apcs_ipc_driver = {
	.probe = qcom_apcs_ipc_probe,
	.remove = qcom_apcs_ipc_remove,
	.driver = {
		.name = "qcom_apcs_ipc",
		.of_match_table = qcom_apcs_ipc_of_match,
	},
};

static int __init qcom_apcs_ipc_init(void)
{
	return platform_driver_register(&qcom_apcs_ipc_driver);
}
postcore_initcall(qcom_apcs_ipc_init);

static void __exit qcom_apcs_ipc_exit(void)
{
	platform_driver_unregister(&qcom_apcs_ipc_driver);
}
module_exit(qcom_apcs_ipc_exit);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Qualcomm APCS IPC driver");