[1/6] tty: n_gsm: Add support for serdev drivers

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -39,6 +39,7 @@ 
 #include <linux/file.h>
 #include <linux/uaccess.h>
 #include <linux/module.h>
+#include <linux/serdev.h>
 #include <linux/timer.h>
 #include <linux/tty_flip.h>
 #include <linux/tty_driver.h>
@@ -50,6 +51,7 @@ 
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/gsmmux.h>
+#include <linux/serdev-gsm.h>
 
 static int debug;
 module_param(debug, int, 0600);
@@ -150,6 +152,7 @@  struct gsm_dlci {
 	/* Data handling callback */
 	void (*data)(struct gsm_dlci *dlci, const u8 *data, int len);
 	void (*prev_data)(struct gsm_dlci *dlci, const u8 *data, int len);
+	struct gsm_serdev_dlci *ops; /* serdev dlci ops, if used */
 	struct net_device *net; /* network interface, if created */
 };
 
@@ -198,6 +201,7 @@  enum gsm_mux_state {
  */
 
 struct gsm_mux {
+	struct gsm_serdev *gsd;		/* Serial device bus data */
 	struct tty_struct *tty;		/* The tty our ldisc is bound to */
 	spinlock_t lock;
 	struct mutex mutex;
@@ -2346,6 +2350,437 @@  static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
 	return 0;
 }
 
+#ifdef CONFIG_SERIAL_DEV_BUS
+
+/**
+ * gsm_serdev_get_config - read ts 27.010 config
+ * @gsd:	serdev-gsm instance
+ * @c:		ts 27.010 config data
+ *
+ * See gsm_copy_config_values() for more information.
+ */
+int gsm_serdev_get_config(struct gsm_serdev *gsd, struct gsm_config *c)
+{
+	struct gsm_mux *gsm;
+
+	if (!gsd || !gsd->gsm)
+		return -ENODEV;
+
+	gsm = gsd->gsm;
+
+	if (!c)
+		return -EINVAL;
+
+	gsm_copy_config_values(gsm, c);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_get_config);
+
+/**
+ * gsm_serdev_set_config - set ts 27.010 config
+ * @gsd:	serdev-gsm instance
+ * @c:		ts 27.010 config data
+ *
+ * See gsm_config() for more information.
+ */
+int gsm_serdev_set_config(struct gsm_serdev *gsd, struct gsm_config *c)
+{
+	struct gsm_mux *gsm;
+
+	if (!gsd || !gsd->serdev || !gsd->gsm)
+		return -ENODEV;
+
+	gsm = gsd->gsm;
+
+	if (!c)
+		return -EINVAL;
+
+	return gsm_config(gsm, c);
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_set_config);
+
+static struct gsm_dlci *gsd_dlci_get(struct gsm_serdev *gsd, int line,
+				     bool allocate)
+{
+	struct gsm_mux *gsm;
+	struct gsm_dlci *dlci;
+
+	if (!gsd || !gsd->gsm)
+		return ERR_PTR(-ENODEV);
+
+	gsm = gsd->gsm;
+
+	if (line < 1 || line >= 63)
+		return ERR_PTR(-EINVAL);
+
+	mutex_lock(&gsm->mutex);
+
+	if (gsm->dlci[line]) {
+		dlci = gsm->dlci[line];
+		goto unlock;
+	} else if (!allocate) {
+		dlci = ERR_PTR(-ENODEV);
+		goto unlock;
+	}
+
+	dlci = gsm_dlci_alloc(gsm, line);
+	if (!dlci) {
+		dlci = ERR_PTR(-ENOMEM);
+		goto unlock;
+	}
+
+	gsm->dlci[line] = dlci;
+
+unlock:
+	mutex_unlock(&gsm->mutex);
+
+	return dlci;
+}
+
+static int gsd_dlci_receive_buf(struct gsm_serdev_dlci *ops,
+				const unsigned char *buf,
+				size_t len)
+{
+	struct gsm_serdev *gsd = ops->gsd;
+	struct gsm_dlci *dlci;
+	struct tty_port *port;
+
+	dlci = gsd_dlci_get(gsd, ops->line, false);
+	if (IS_ERR(dlci))
+		return PTR_ERR(dlci);
+
+	port = &dlci->port;
+	tty_insert_flip_string(port, buf, len);
+	tty_flip_buffer_push(port);
+
+	return len;
+}
+
+static void gsd_dlci_data(struct gsm_dlci *dlci, const u8 *buf, int len)
+{
+	struct gsm_mux *gsm = dlci->gsm;
+	struct gsm_serdev *gsd = gsm->gsd;
+
+	if (!gsd || !dlci->ops)
+		return;
+
+	switch (dlci->adaption) {
+	case 0:
+	case 1:
+		if (dlci->ops->receive_buf)
+			dlci->ops->receive_buf(dlci->ops, buf, len);
+		break;
+	default:
+		pr_warn("dlci%i adaption %i not yet implemented\n",
+			dlci->addr, dlci->adaption);
+		break;
+	}
+}
+
+/**
+ * gsm_serdev_write - write data to a ts 27.010 channel
+ * @gsd:	serdev-gsm instance
+ * @ops:	channel ops
+ * @buf:	write buffer
+ * @len:	buffer length
+ */
+int gsm_serdev_write(struct gsm_serdev *gsd, struct gsm_serdev_dlci *ops,
+		     const u8 *buf, int len)
+{
+	struct gsm_mux *gsm;
+	struct gsm_dlci *dlci;
+	struct gsm_msg *msg;
+	int h, size, total_size = 0;
+	u8 *dp;
+
+	if (!gsd || !gsd->gsm)
+		return -ENODEV;
+
+	gsm = gsd->gsm;
+
+	dlci = gsd_dlci_get(gsd, ops->line, false);
+	if (IS_ERR(dlci))
+		return PTR_ERR(dlci);
+
+	h = dlci->adaption - 1;
+
+	if (len > gsm->mtu)
+		len = gsm->mtu;
+
+	size = len + h;
+
+	msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
+	if (!msg)
+		return -ENOMEM;
+
+	dp = msg->data;
+	switch (dlci->adaption) {
+	case 1:
+		break;
+	case 2:
+		*dp++ = gsm_encode_modem(dlci);
+		break;
+	}
+	memcpy(dp, buf, len);
+	gsm_data_queue(dlci, msg);
+	total_size += size;
+
+	return total_size;
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_write);
+
+/**
+ * gsm_serdev_data_kick - indicate more data can be transmitted
+ * @gsd:	serdev-gsm instance
+ *
+ * See gsm_data_kick() for more information.
+ */
+void gsm_serdev_data_kick(struct gsm_serdev *gsd)
+{
+	struct gsm_mux *gsm;
+	unsigned long flags;
+
+	if (!gsd || !gsd->gsm)
+		return;
+
+	gsm = gsd->gsm;
+
+	spin_lock_irqsave(&gsm->tx_lock, flags);
+	gsm_data_kick(gsm);
+	spin_unlock_irqrestore(&gsm->tx_lock, flags);
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_data_kick);
+
+/**
+ * gsm_serdev_register_dlci - register a ts 27.010 channel
+ * @gsd:	serdev-gsm instance
+ * @ops:	channel ops
+ */
+int gsm_serdev_register_dlci(struct gsm_serdev *gsd,
+			     struct gsm_serdev_dlci *ops)
+{
+	struct gsm_dlci *dlci;
+	struct gsm_mux *gsm;
+	int retries;
+
+	if (!gsd || !gsd->gsm || !gsd->serdev)
+		return -ENODEV;
+
+	gsm = gsd->gsm;
+
+	if (!ops || !ops->line)
+		return -EINVAL;
+
+	dlci = gsd_dlci_get(gsd, ops->line, true);
+	if (IS_ERR(dlci))
+		return PTR_ERR(dlci);
+
+	if (dlci->state == DLCI_OPENING || dlci->state == DLCI_OPEN ||
+	    dlci->state == DLCI_CLOSING)
+		return -EBUSY;
+
+	mutex_lock(&dlci->mutex);
+	ops->gsd = gsd;
+	dlci->ops = ops;
+	dlci->modem_rx = 0;
+	dlci->prev_data = dlci->data;
+	dlci->data = gsd_dlci_data;
+	mutex_unlock(&dlci->mutex);
+
+	gsm_dlci_begin_open(dlci);
+
+	/*
+	 * Allow some time for dlci to move to DLCI_OPEN state. Otherwise
+	 * the serdev consumer driver can start sending data too early during
+	 * the setup, and the response will be missed by gms_queue() if we
+	 * still have DLCI_CLOSED state.
+	 */
+	for (retries = 10; retries > 0; retries--) {
+		if (dlci->state == DLCI_OPEN)
+			break;
+		msleep(100);
+	}
+
+	if (!retries)
+		dev_dbg(&gsd->serdev->dev, "dlci%i not currently active\n",
+			dlci->addr);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_register_dlci);
+
+/**
+ * gsm_serdev_unregister_dlci - unregister a ts 27.010 channel
+ * @gsd:	serdev-gsm instance
+ * @ops:	channel ops
+ */
+void gsm_serdev_unregister_dlci(struct gsm_serdev *gsd,
+				struct gsm_serdev_dlci *ops)
+{
+	struct gsm_mux *gsm;
+	struct gsm_dlci *dlci;
+
+	if (!gsd || !gsd->gsm || !gsd->serdev)
+		return;
+
+	gsm = gsd->gsm;
+
+	if (!ops || !ops->line)
+		return;
+
+	dlci = gsd_dlci_get(gsd, ops->line, false);
+	if (IS_ERR(dlci))
+		return;
+
+	mutex_lock(&dlci->mutex);
+	gsm_destroy_network(dlci);
+	dlci->data = dlci->prev_data;
+	dlci->ops->gsd = NULL;
+	dlci->ops = NULL;
+	mutex_unlock(&dlci->mutex);
+
+	gsm_dlci_begin_close(dlci);
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_unregister_dlci);
+
+static int gsm_serdev_output(struct gsm_mux *gsm, u8 *data, int len)
+{
+	struct serdev_device *serdev = gsm->gsd->serdev;
+
+	if (gsm->gsd->output)
+		return gsm->gsd->output(gsm->gsd, data, len);
+	else
+		return serdev_device_write_buf(serdev, data, len);
+}
+
+static int gsd_receive_buf(struct serdev_device *serdev, const u8 *data,
+			   size_t count)
+{
+	struct gsm_serdev *gsd = serdev_device_get_drvdata(serdev);
+	struct gsm_mux *gsm;
+	const unsigned char *dp;
+	int i;
+
+	if (WARN_ON(!gsd))
+		return 0;
+
+	gsm = gsd->gsm;
+
+	if (debug & 4)
+		print_hex_dump_bytes("gsd_receive_buf: ",
+				     DUMP_PREFIX_OFFSET,
+				     data, count);
+
+	for (i = count, dp = data; i; i--, dp++)
+		gsm->receive(gsm, *dp);
+
+	return count;
+}
+
+static void gsd_write_wakeup(struct serdev_device *serdev)
+{
+	serdev_device_write_wakeup(serdev);
+}
+
+static struct serdev_device_ops gsd_client_ops = {
+	.receive_buf = gsd_receive_buf,
+	.write_wakeup = gsd_write_wakeup,
+};
+
+int gsm_serdev_register_tty_port(struct gsm_serdev *gsd, int line)
+{
+	struct gsm_serdev_dlci *ops;
+	unsigned int base;
+	int error;
+
+	if (line < 1)
+		return -EINVAL;
+
+	ops = kzalloc(sizeof(*ops), GFP_KERNEL);
+	if (!ops)
+		return -ENOMEM;
+
+	ops->line = line;
+	ops->receive_buf = gsd_dlci_receive_buf;
+
+	error = gsm_serdev_register_dlci(gsd, ops);
+	if (error) {
+		kfree(ops);
+
+		return error;
+	}
+
+	base = mux_num_to_base(gsd->gsm);
+	tty_register_device(gsm_tty_driver, base + ops->line, NULL);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_register_tty_port);
+
+void gsm_serdev_unregister_tty_port(struct gsm_serdev *gsd, int line)
+{
+	struct gsm_dlci *dlci;
+	unsigned int base;
+
+	if (line < 1)
+		return;
+
+	dlci = gsd_dlci_get(gsd, line, false);
+	if (IS_ERR(dlci))
+		return;
+
+	base = mux_num_to_base(gsd->gsm);
+	tty_unregister_device(gsm_tty_driver, base + line);
+	gsm_serdev_unregister_dlci(gsd, dlci->ops);
+	kfree(dlci->ops);
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_unregister_tty_port);
+
+int gsm_serdev_register_device(struct gsm_serdev *gsd)
+{
+	struct gsm_mux *gsm;
+	int error;
+
+	if (WARN(!gsd || !gsd->serdev || !gsd->output,
+		 "serdev and output must be initialized\n"))
+		return -EINVAL;
+
+	serdev_device_set_client_ops(gsd->serdev, &gsd_client_ops);
+
+	gsm = gsm_alloc_mux();
+	if (!gsm)
+		return -ENOMEM;
+
+	gsm->encoding = 1;
+	gsm->tty = NULL;
+	gsm->gsd = gsd;
+	gsm->output = gsm_serdev_output;
+	gsd->gsm = gsm;
+	mux_get(gsd->gsm);
+
+	error = gsm_activate_mux(gsd->gsm);
+	if (error) {
+		gsm_cleanup_mux(gsd->gsm);
+		mux_put(gsd->gsm);
+
+		return error;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_register_device);
+
+void gsm_serdev_unregister_device(struct gsm_serdev *gsd)
+{
+	gsm_cleanup_mux(gsd->gsm);
+	mux_put(gsd->gsm);
+	gsd->gsm = NULL;
+}
+EXPORT_SYMBOL_GPL(gsm_serdev_unregister_device);
+
+#endif	/* CONFIG_SERIAL_DEV_BUS */
+
 /**
  *	gsmld_output		-	write to link
  *	@gsm: our mux
diff --git a/include/linux/serdev-gsm.h b/include/linux/serdev-gsm.h
new file mode 100644
--- /dev/null
+++ b/include/linux/serdev-gsm.h
@@ -0,0 +1,154 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_SERDEV_GSM_H
+#define _LINUX_SERDEV_GSM_H
+
+#include <linux/device.h>
+#include <linux/serdev.h>
+#include <linux/types.h>
+
+struct gsm_serdev_dlci;
+struct gsm_config;
+
+/**
+ * struct gsm_serdev - serdev-gsm instance
+ * @serdev:		serdev instance
+ * @gsm:		ts 27.010 n_gsm instance
+ * @drvdata:		serdev-gsm consumer driver data
+ * @output:		read data from ts 27.010 channel
+ *
+ * Currently only serdev and output must be initialized, the rest are
+ * are initialized by gsm_serdev_register_dlci().
+ */
+struct gsm_serdev {
+	struct serdev_device *serdev;
+	struct gsm_mux *gsm;
+	void *drvdata;
+	int (*output)(struct gsm_serdev *gsd, u8 *data, int len);
+};
+
+/**
+ * struct gsm_serdev_dlci - serdev-gsm ts 27.010 channel data
+ * @gsd:		serdev-gsm instance
+ * @line:		ts 27.010 channel, control channel 0 is not available
+ * @receive_buf:	function to handle data received for the channel
+ * @drvdata:		dlci specific consumer driver data
+ */
+struct gsm_serdev_dlci {
+	struct gsm_serdev *gsd;
+	int line;
+	int (*receive_buf)(struct gsm_serdev_dlci *ops,
+			   const unsigned char *buf,
+			   size_t len);
+	void *drvdata;
+};
+
+#if IS_ENABLED(CONFIG_N_GSM) && IS_ENABLED(CONFIG_SERIAL_DEV_BUS)
+
+extern int gsm_serdev_register_device(struct gsm_serdev *gsd);
+extern void gsm_serdev_unregister_device(struct gsm_serdev *gsd);
+extern int gsm_serdev_register_tty_port(struct gsm_serdev *gsd, int line);
+extern void gsm_serdev_unregister_tty_port(struct gsm_serdev *gsd, int line);
+
+static inline void *gsm_serdev_get_drvdata(struct device *dev)
+{
+	struct serdev_device *serdev = to_serdev_device(dev);
+	struct gsm_serdev *gsd = serdev_device_get_drvdata(serdev);
+
+	if (gsd)
+		return gsd->drvdata;
+
+	return NULL;
+}
+
+static inline void gsm_serdev_set_drvdata(struct device *dev, void *drvdata)
+{
+	struct serdev_device *serdev = to_serdev_device(dev);
+	struct gsm_serdev *gsd = serdev_device_get_drvdata(serdev);
+
+	if (gsd)
+		gsd->drvdata = drvdata;
+}
+
+extern int gsm_serdev_get_config(struct gsm_serdev *gsd, struct gsm_config *c);
+extern int gsm_serdev_set_config(struct gsm_serdev *gsd, struct gsm_config *c);
+extern int
+gsm_serdev_register_dlci(struct gsm_serdev *gsd, struct gsm_serdev_dlci *ops);
+extern void
+gsm_serdev_unregister_dlci(struct gsm_serdev *gsd, struct gsm_serdev_dlci *ops);
+extern int gsm_serdev_write(struct gsm_serdev *gsd, struct gsm_serdev_dlci *ops,
+			    const u8 *buf, int len);
+extern void gsm_serdev_data_kick(struct gsm_serdev *gsd);
+
+#else	/* CONFIG_SERIAL_DEV_BUS */
+
+static inline
+int gsm_serdev_register_device(struct gsm_serdev *gsd)
+{
+	return -ENODEV;
+}
+
+static inline void gsm_serdev_unregister_device(struct gsm_serdev *gsd)
+{
+}
+
+static inline int
+gsm_serdev_register_tty_port(struct gsm_serdev *gsd, int line)
+{
+	return -ENODEV;
+}
+
+static inline
+void gsm_serdev_unregister_tty_port(struct gsm_serdev *gsd, int line)
+{
+}
+
+static inline void *gsm_serdev_get_drvdata(struct device *dev)
+{
+	return NULL;
+}
+
+static inline
+void gsm_serdev_set_drvdata(struct device *dev, void *drvdata)
+{
+}
+
+static inline
+int gsm_serdev_get_config(struct gsm_serdev *gsd, struct gsm_config *c)
+{
+	return -ENODEV;
+}
+
+static inline
+int gsm_serdev_set_config(struct gsm_serdev *gsd, struct gsm_config *c)
+{
+	return -ENODEV;
+}
+
+static inline
+int gsm_serdev_register_dlci(struct gsm_serdev *gsd,
+			     struct gsm_serdev_dlci *ops)
+{
+	return -ENODEV;
+}
+
+static inline
+void gsm_serdev_unregister_dlci(struct gsm_serdev *gsd,
+				struct gsm_serdev_dlci *ops)
+{
+}
+
+static inline
+int gsm_serdev_write(struct gsm_serdev *gsd, struct gsm_serdev_dlci *ops,
+		     const u8 *buf, int len)
+{
+	return -ENODEV;
+}
+
+static inline
+void gsm_serdev_data_kick(struct gsm_serdev *gsd)
+{
+}
+
+#endif	/* CONFIG_N_GSM && CONFIG_SERIAL_DEV_BUS */
+#endif	/* _LINUX_SERDEV_GSM_H */