/*
 * nokia-modem.c
 *
 * HSI client driver for Nokia N900 modem.
 *
 * Copyright (C) 2014 Sebastian Reichel <sre@kernel.org>
 *
 * 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.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/gpio/consumer.h>
#include <linux/hsi/hsi.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_gpio.h>
#include <linux/hsi/ssi_protocol.h>

static unsigned int pm;
module_param(pm, int, 0400);
MODULE_PARM_DESC(pm,
	"Enable power management (0=disabled, 1=userland based [default])");

struct nokia_modem_gpio {
	struct gpio_desc	*gpio;
	const char		*name;
};

struct nokia_modem_device {
	struct tasklet_struct	nokia_modem_rst_ind_tasklet;
	int			nokia_modem_rst_ind_irq;
	struct device		*device;
	struct nokia_modem_gpio	*gpios;
	int			gpio_amount;
	struct hsi_client	*ssi_protocol;
};

static void do_nokia_modem_rst_ind_tasklet(unsigned long data)
{
	struct nokia_modem_device *modem = (struct nokia_modem_device *)data;

	if (!modem)
		return;

	dev_info(modem->device, "CMT rst line change detected\n");

	if (modem->ssi_protocol)
		ssip_reset_event(modem->ssi_protocol);
}

static irqreturn_t nokia_modem_rst_ind_isr(int irq, void *data)
{
	struct nokia_modem_device *modem = (struct nokia_modem_device *)data;

	tasklet_schedule(&modem->nokia_modem_rst_ind_tasklet);

	return IRQ_HANDLED;
}

static void nokia_modem_gpio_unexport(struct device *dev)
{
	struct nokia_modem_device *modem = dev_get_drvdata(dev);
	int i;

	for (i = 0; i < modem->gpio_amount; i++) {
		sysfs_remove_link(&dev->kobj, modem->gpios[i].name);
		gpiod_unexport(modem->gpios[i].gpio);
	}
}

static int nokia_modem_gpio_probe(struct device *dev)
{
	struct device_node *np = dev->of_node;
	struct nokia_modem_device *modem = dev_get_drvdata(dev);
	int gpio_count, gpio_name_count, i, err;

	gpio_count = of_gpio_count(np);

	if (gpio_count < 0) {
		dev_err(dev, "missing gpios: %d\n", gpio_count);
		return gpio_count;
	}

	gpio_name_count = of_property_count_strings(np, "gpio-names");

	if (gpio_count != gpio_name_count) {
		dev_err(dev, "number of gpios does not equal number of gpio names\n");
		return -EINVAL;
	}

	modem->gpios = devm_kzalloc(dev, gpio_count *
				sizeof(struct nokia_modem_gpio), GFP_KERNEL);
	if (!modem->gpios) {
		dev_err(dev, "Could not allocate memory for gpios\n");
		return -ENOMEM;
	}

	modem->gpio_amount = gpio_count;

	for (i = 0; i < gpio_count; i++) {
		modem->gpios[i].gpio = devm_gpiod_get_index(dev, NULL, i);
		if (IS_ERR(modem->gpios[i].gpio)) {
			dev_err(dev, "Could not get gpio %d\n", i);
			return PTR_ERR(modem->gpios[i].gpio);
		}

		err = of_property_read_string_index(np, "gpio-names", i,
						&(modem->gpios[i].name));
		if (err) {
			dev_err(dev, "Could not get gpio name %d\n", i);
			return err;
		}

		err = gpiod_direction_output(modem->gpios[i].gpio, 0);
		if (err)
			return err;

		err = gpiod_export(modem->gpios[i].gpio, 0);
		if (err)
			return err;

		err = gpiod_export_link(dev, modem->gpios[i].name,
							modem->gpios[i].gpio);
		if (err)
			return err;
	}

	return 0;
}

static int nokia_modem_probe(struct device *dev)
{
	struct device_node *np;
	struct nokia_modem_device *modem;
	struct hsi_client *cl = to_hsi_client(dev);
	struct hsi_port *port = hsi_get_port(cl);
	int irq, pflags, err;
	struct hsi_board_info ssip;

	np = dev->of_node;
	if (!np) {
		dev_err(dev, "device tree node not found\n");
		return -ENXIO;
	}

	modem = devm_kzalloc(dev, sizeof(*modem), GFP_KERNEL);
	if (!modem) {
		dev_err(dev, "Could not allocate memory for nokia_modem_device\n");
		return -ENOMEM;
	}
	dev_set_drvdata(dev, modem);

	irq = irq_of_parse_and_map(np, 0);
	if (irq < 0) {
		dev_err(dev, "Invalid rst_ind interrupt (%d)\n", irq);
		return irq;
	}
	modem->nokia_modem_rst_ind_irq = irq;
	pflags = irq_get_trigger_type(irq);

	tasklet_init(&modem->nokia_modem_rst_ind_tasklet,
			do_nokia_modem_rst_ind_tasklet, (unsigned long)modem);
	err = devm_request_irq(dev, irq, nokia_modem_rst_ind_isr,
				IRQF_DISABLED | pflags, "modem_rst_ind", modem);
	if (err < 0) {
		dev_err(dev, "Request rst_ind irq(%d) failed (flags %d)\n",
								irq, pflags);
		return err;
	}
	enable_irq_wake(irq);

	if(pm) {
		err = nokia_modem_gpio_probe(dev);
		if (err < 0) {
			dev_err(dev, "Could not probe GPIOs\n");
			goto error1;
		}
	}

	ssip.name = "ssi-protocol";
	ssip.tx_cfg = cl->tx_cfg;
	ssip.rx_cfg = cl->rx_cfg;
	ssip.platform_data = NULL;
	ssip.archdata = NULL;

	modem->ssi_protocol = hsi_new_client(port, &ssip);
	if (!modem->ssi_protocol) {
		dev_err(dev, "Could not register ssi-protocol device\n");
		goto error2;
	}

	err = device_attach(&modem->ssi_protocol->device);
	if (err == 0) {
		dev_err(dev, "Missing ssi-protocol driver\n");
		err = -EPROBE_DEFER;
		goto error3;
	} else if (err < 0) {
		dev_err(dev, "Could not load ssi-protocol driver (%d)\n", err);
		goto error3;
	}

	/* TODO: register cmt-speech hsi client */

	dev_info(dev, "Registered Nokia HSI modem\n");

	return 0;

error3:
	hsi_remove_client(&modem->ssi_protocol->device, NULL);
error2:
	nokia_modem_gpio_unexport(dev);
error1:
	disable_irq_wake(modem->nokia_modem_rst_ind_irq);
	tasklet_kill(&modem->nokia_modem_rst_ind_tasklet);

	return err;
}

static int nokia_modem_remove(struct device *dev)
{
	struct nokia_modem_device *modem = dev_get_drvdata(dev);

	if (!modem)
		return 0;

	if (modem->ssi_protocol) {
		hsi_remove_client(&modem->ssi_protocol->device, NULL);
		modem->ssi_protocol = NULL;
	}

	nokia_modem_gpio_unexport(dev);
	dev_set_drvdata(dev, NULL);
	disable_irq_wake(modem->nokia_modem_rst_ind_irq);
	tasklet_kill(&modem->nokia_modem_rst_ind_tasklet);

	return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id nokia_modem_of_match[] = {
	{ .compatible = "nokia,n900-modem", },
	{},
};
MODULE_DEVICE_TABLE(of, nokia_modem_of_match);
#endif

static struct hsi_client_driver nokia_modem_driver = {
	.driver = {
		.name	= "nokia-modem",
		.owner	= THIS_MODULE,
		.probe	= nokia_modem_probe,
		.remove	= nokia_modem_remove,
		.of_match_table = of_match_ptr(nokia_modem_of_match),
	},
};

static int __init nokia_modem_init(void)
{
	return hsi_register_client_driver(&nokia_modem_driver);
}
module_init(nokia_modem_init);

static void __exit nokia_modem_exit(void)
{
	hsi_unregister_client_driver(&nokia_modem_driver);
}
module_exit(nokia_modem_exit);

MODULE_ALIAS("hsi:nokia-modem");
MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
MODULE_DESCRIPTION("HSI driver module for Nokia N900 Modem");
MODULE_LICENSE("GPL");