root/drivers/hsi/clients/nokia-modem.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * nokia-modem.c
 *
 * HSI client driver for Nokia N900 modem.
 *
 * Copyright (C) 2014 Sebastian Reichel <sre@kernel.org>
 */

#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/hsi/ssi_protocol.h>

static unsigned int pm = 1;
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;
        struct hsi_client       *cmt_speech;
};

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 = gpiod_count(dev, NULL);
        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_kcalloc(dev, gpio_count, sizeof(*modem->gpios),
                                    GFP_KERNEL);
        if (!modem->gpios)
                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,
                                                            GPIOD_OUT_LOW);
                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_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;
        struct hsi_board_info cmtspeech;

        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)
                return -ENOMEM;

        dev_set_drvdata(dev, modem);
        modem->device = dev;

        irq = irq_of_parse_and_map(np, 0);
        if (!irq) {
                dev_err(dev, "Invalid rst_ind interrupt (%d)\n", irq);
                return -EINVAL;
        }
        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,
                                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");
                err = -ENOMEM;
                goto error2;
        }

        err = device_attach(&modem->ssi_protocol->device);
        if (err == 0) {
                dev_dbg(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;
        }

        cmtspeech.name = "cmt-speech";
        cmtspeech.tx_cfg = cl->tx_cfg;
        cmtspeech.rx_cfg = cl->rx_cfg;
        cmtspeech.platform_data = NULL;
        cmtspeech.archdata = NULL;

        modem->cmt_speech = hsi_new_client(port, &cmtspeech);
        if (!modem->cmt_speech) {
                dev_err(dev, "Could not register cmt-speech device\n");
                err = -ENOMEM;
                goto error3;
        }

        err = device_attach(&modem->cmt_speech->device);
        if (err == 0) {
                dev_dbg(dev, "Missing cmt-speech driver\n");
                err = -EPROBE_DEFER;
                goto error4;
        } else if (err < 0) {
                dev_err(dev, "Could not load cmt-speech driver (%d)\n", err);
                goto error4;
        }

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

        return 0;

error4:
        hsi_remove_client(&modem->cmt_speech->device, NULL);
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->cmt_speech) {
                hsi_remove_client(&modem->cmt_speech->device, NULL);
                modem->cmt_speech = NULL;
        }

        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", },
        { .compatible = "nokia,n950-modem", },
        { .compatible = "nokia,n9-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");