[PATCHv4 1/4] modem_shm: Add Modem Access Framework

@@ -152,4 +152,6 @@ source "drivers/vme/Kconfig"
 
 source "drivers/pwm/Kconfig"
 
+source "drivers/modem_shm/Kconfig"
+
 endmenu

@@ -139,3 +139,4 @@ obj-$(CONFIG_EXTCON)		+= extcon/
 obj-$(CONFIG_MEMORY)		+= memory/
 obj-$(CONFIG_IIO)		+= iio/
 obj-$(CONFIG_VME_BUS)		+= vme/
+obj-$(CONFIG_MODEM_SHM)		+= modem_shm/

@@ -0,0 +1,9 @@
+config MODEM_SHM
+        bool "Modem Access Framework"
+        default n
+        help
+         Add support for Modem Access Framework. It allows different
+	 platform specific drivers to register modem access mechanisms
+	 and allows transparent access to modem to the client drivers.
+
+	 If unsure, say N.

@@ -0,0 +1 @@
+obj-$(CONFIG_MODEM_SHM)		:= modem_access.o

@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Kumar Sanghvi
+ *	Arun Murthy <arun.murthy@stericsson.com>
+ *
+ * Heavily adapted from Regulator framework.
+ * Provides mechanisms for registering platform specific access
+ * mechanisms for modem.
+ * Also, exposes APIs for gettng/releasing the access and even
+ * query the access status, and the modem usage status.
+ */
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/printk.h>
+#include <linux/modem_shm/modem.h>
+
+static struct class *modem_class;
+
+static int __modem_is_requested(struct device *dev, void *data)
+{
+	struct modem_desc *mdesc = (struct modem_desc *)data;
+
+	if (!mdesc->mclients) {
+		printk(KERN_ERR "modem_access: modem description is NULL\n");
+		return 0;
+	}
+	return atomic_read(&mdesc->mclients->cnt);
+}
+
+int modem_is_requested(struct modem_desc *mdesc)
+{
+	return class_for_each_device(modem_class, NULL, (void *)mdesc, __modem_is_requested);
+}
+
+int modem_release(struct modem_desc *mdesc)
+{
+	if (!mdesc->release)
+		return -EFAULT;
+
+	if (modem_is_requested(mdesc)) {
+		atomic_dec(&mdesc->mclients->cnt);
+		if (atomic_read(&mdesc->use_cnt) == 1) {
+			mdesc->release(mdesc);
+			atomic_dec(&mdesc->use_cnt);
+		}
+	} else
+		printk(KERN_WARNING
+			"modem_shm: client %s has not requested modem to release\n",
+			mdesc->mclients->name);
+	return 0;
+}
+
+int modem_request(struct modem_desc *mdesc)
+{
+	if (!mdesc->request)
+		return -EFAULT;
+
+	if (atomic_read(&mdesc->mclients->cnt) == 0) {
+		mdesc->request(mdesc);
+		atomic_inc(&mdesc->mclients->cnt);
+		atomic_inc(&mdesc->use_cnt);
+		if (atomic_read(&mdesc->use_cnt) > mdesc->no_clients) {
+			dev_warn(mdesc->dev,
+					"modem_shm: mismatch in the modem count\n");
+		}
+	} else
+		dev_warn(mdesc->dev,
+				"modem_shm: client '%s' has already requested modem\n",
+				dev_name(mdesc->mclients->dev));
+	return 0;
+}
+
+int modem_put(struct modem_desc *mdesc)
+{
+	if (atomic_read(&mdesc->cli_cnt)) {
+		atomic_dec(&mdesc->cli_cnt);
+		kfree(mdesc->mclients);
+		return 0;
+	} else {
+		dev_err(mdesc->dev, "mismatch in the no of clients\n");
+		return -EFAULT;
+	}
+}
+
+static int modem_match_device_by_name(struct device *dev, void *data)
+{
+	const char *name = data;
+	struct modem_desc *mdesc = dev_get_drvdata(dev);
+
+	return strcmp(mdesc->name, name) == 0;
+}
+
+struct modem_desc *modem_get(struct device *pdev, const char *name)
+{
+	struct clients *mcli;
+	struct modem_desc *mdesc = NULL;
+	struct device *dev = class_find_device(modem_class, NULL, (void *)name,
+			modem_match_device_by_name);
+	mdesc = dev ? dev_get_drvdata(dev): NULL;
+	if (mdesc) {
+		if (atomic_read(&mdesc->cli_cnt) >= mdesc->no_clients) {
+			dev_err(pdev, "already %d clients have requested\n",
+					mdesc->no_clients);
+			return NULL;
+		}
+		mcli = kzalloc(sizeof(struct clients), GFP_KERNEL);
+		if (!mcli) {
+			dev_err(pdev, "uanable to allocate memory\n");
+			return NULL;
+		}
+		mdesc->mclients = mcli;
+		mdesc->mclients->dev = pdev;
+		atomic_inc(&mdesc->cli_cnt);
+		atomic_set(&mdesc->mclients->cnt, 0);
+	}
+	return mdesc;
+}
+
+int modem_register(struct device *parent, struct modem_desc *mdesc)
+{
+	mdesc->dev = device_create(modem_class, parent, 0, mdesc, "%s", mdesc->name);
+	if (IS_ERR(mdesc->dev)) {
+		dev_err(parent, "failed to create device\n");
+		return PTR_ERR(mdesc->dev);
+	}
+
+	atomic_set(&mdesc->use_cnt, 0);
+	atomic_set(&mdesc->cli_cnt, 0);
+	return 0;
+}
+
+int modem_unregister(struct modem_desc *mdesc)
+{
+	device_unregister(mdesc->dev);
+	return 0;
+}
+
+static int modem_init(void)
+{
+	modem_class = class_create(THIS_MODULE, "modem_access");
+	if (IS_ERR(modem_class)) {
+		printk(KERN_ERR "modem_access: unable to create class\n");
+		return PTR_ERR(modem_class);
+	}
+
+	if (modem_class == NULL || IS_ERR(modem_class))
+		printk(KERN_ERR "modem_access: MODEM ERR0R");
+
+	return 0;
+}
+
+static void modem_exit(void)
+{
+	class_destroy(modem_class);
+}
+
+arch_initcall(modem_init);
+module_exit(modem_exit);

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Kumar Sanghvi
+ *	Arun Murthy <arun.murthy@stericsson.com>
+ *
+ * Heavily adapted from Regulator framework
+ */
+#ifndef __MODEM_H__
+#define __MODEM_H__
+
+#include <linux/device.h>
+
+struct clients {
+	struct device *dev;
+	const char *name;
+	atomic_t cnt;
+};
+
+struct modem_desc {
+	int (*request)(struct modem_desc *);
+	void (*release)(struct modem_desc *);
+	int (*is_requested)(struct modem_desc *);
+	struct clients *mclients;
+	struct device *dev;
+	char *name;
+	u8 no_clients;
+	atomic_t use_cnt;
+	atomic_t cli_cnt;
+};
+
+#ifdef CONFIG_MODEM_SHM
+int modem_register(struct device *parent, struct modem_desc *mdesc);
+int modem_unregister(struct modem_desc *mdesc);
+struct modem_desc *modem_get(struct device *dev, const char *name);
+int modem_put(struct modem_desc *mdesc);
+int modem_release(struct modem_desc *mdesc);
+int modem_is_requested(struct modem_desc *mdesc);
+int modem_request(struct modem_desc *mdesc);
+
+
+#else
+int modem_register(struct device *parent, struct modem_desc *mdesc)
+{
+	return NULL;
+}
+
+static inline int modem_unregister(struct modem_desc *mdesc)
+{
+	return NULL;
+}
+#endif
+#endif /* __MODEM_H__ */