[PATCH v7 04/13] slimbus: core: Add slim controllers support

From: srinivas . kandagatla
Date: Wed Nov 15 2017 - 09:14:46 EST

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From: Sagar Dharia <sdharia@xxxxxxxxxxxxxx>

This patch adds support to slim controllers in the slim core,
including some utility functions invoked by the controller and
slim device drivers.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
drivers/slimbus/core.c | 312 ++++++++++++++++++++++++++++++++++++++++++++++
drivers/slimbus/slimbus.h | 116 +++++++++++++++++
include/linux/slimbus.h | 7 ++
3 files changed, 435 insertions(+)
create mode 100644 drivers/slimbus/slimbus.h

diff --git a/drivers/slimbus/core.c b/drivers/slimbus/core.c
index 22edebf1a233..d31a9c4fe7e9 100644
--- a/drivers/slimbus/core.c
+++ b/drivers/slimbus/core.c
@@ -14,7 +14,11 @@
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/init.h>
+#include <linux/idr.h>
#include <linux/slimbus.h>
+#include "slimbus.h"
+
+static DEFINE_IDA(ctrl_ida);

static const struct slim_device_id *slim_match(const struct slim_device_id *id,
const struct slim_device *sbdev)
@@ -106,6 +110,314 @@ void slim_driver_unregister(struct slim_driver *drv)
}
EXPORT_SYMBOL_GPL(slim_driver_unregister);

+static void slim_dev_release(struct device *dev)
+{
+ struct slim_device *sbdev = to_slim_device(dev);
+
+ put_device(sbdev->ctrl->dev);
+ kfree(sbdev);
+}
+
+static int slim_add_device(struct slim_controller *ctrl,
+ struct slim_device *sbdev,
+ struct device_node *node)
+{
+ sbdev->dev.bus = &slimbus_bus;
+ sbdev->dev.parent = ctrl->dev;
+ sbdev->dev.release = slim_dev_release;
+ sbdev->dev.driver = NULL;
+ sbdev->ctrl = ctrl;
+
+ dev_set_name(&sbdev->dev, "%x:%x:%x:%x",
+ sbdev->e_addr.manf_id,
+ sbdev->e_addr.prod_code,
+ sbdev->e_addr.dev_index,
+ sbdev->e_addr.instance);
+
+ get_device(ctrl->dev);
+
+ return device_register(&sbdev->dev);
+}
+
+static struct slim_device *slim_alloc_device(struct slim_controller *ctrl,
+ struct slim_eaddr *eaddr,
+ struct device_node *node)
+{
+ struct slim_device *sbdev;
+ int ret;
+
+ sbdev = kzalloc(sizeof(struct slim_device), GFP_KERNEL);
+ if (!sbdev)
+ return NULL;
+
+ sbdev->e_addr = *eaddr;
+ ret = slim_add_device(ctrl, sbdev, node);
+ if (ret) {
+ kfree(sbdev);
+ return NULL;
+ }
+
+ return sbdev;
+}
+
+/*
+ * slim_register_controller() - Controller bring-up and registration.
+ *
+ * @ctrl: Controller to be registered.
+ *
+ * A controller is registered with the framework using this API.
+ * If devices on a controller were registered before controller,
+ * this will make sure that they get probed when controller is up
+ */
+int slim_register_controller(struct slim_controller *ctrl)
+{
+ int id;
+
+ id = ida_simple_get(&ctrl_ida, 0, 0, GFP_KERNEL);
+ if (id < 0)
+ return id;
+
+ ctrl->id = id;
+
+ if (!ctrl->min_cg)
+ ctrl->min_cg = SLIM_MIN_CLK_GEAR;
+ if (!ctrl->max_cg)
+ ctrl->max_cg = SLIM_MAX_CLK_GEAR;
+
+ ida_init(&ctrl->laddr_ida);
+ idr_init(&ctrl->tid_idr);
+ mutex_init(&ctrl->lock);
+
+ dev_dbg(ctrl->dev, "Bus [%s] registered:dev:%p\n",
+ ctrl->name, ctrl->dev);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(slim_register_controller);
+
+/* slim_remove_device: Remove the effect of slim_add_device() */
+static void slim_remove_device(struct slim_device *sbdev)
+{
+ device_unregister(&sbdev->dev);
+}
+
+static int slim_ctrl_remove_device(struct device *dev, void *null)
+{
+ slim_remove_device(to_slim_device(dev));
+ return 0;
+}
+
+/**
+ * slim_unregister_controller() - Controller tear-down.
+ *
+ * @ctrl: Controller to tear-down.
+ */
+int slim_unregister_controller(struct slim_controller *ctrl)
+{
+ /* Remove all clients */
+ device_for_each_child(ctrl->dev, NULL, slim_ctrl_remove_device);
+ ida_simple_remove(&ctrl_ida, ctrl->id);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(slim_unregister_controller);
+
+static void slim_device_update_status(struct slim_device *sbdev,
+ enum slim_device_status status)
+{
+ struct slim_driver *sbdrv;
+
+ if (sbdev->status == status)
+ return;
+
+ sbdev->status = status;
+ if (!sbdev->dev.driver)
+ return;
+
+ sbdrv = to_slim_driver(sbdev->dev.driver);
+ if (sbdrv->device_status)
+ sbdrv->device_status(sbdev, sbdev->status);
+}
+
+/**
+ * slim_report_absent() - Controller calls this function when a device
+ * reports absent, OR when the device cannot be communicated with
+ *
+ * @sbdev: Device that cannot be reached, or sent report absent
+ */
+void slim_report_absent(struct slim_device *sbdev)
+{
+ struct slim_controller *ctrl = sbdev->ctrl;
+
+ if (!ctrl)
+ return;
+
+ /* invalidate logical addresses */
+ mutex_lock(&ctrl->lock);
+ sbdev->is_laddr_valid = false;
+ mutex_unlock(&ctrl->lock);
+
+ ida_simple_remove(&ctrl->laddr_ida, sbdev->laddr);
+ slim_device_update_status(sbdev, SLIM_DEVICE_STATUS_DOWN);
+}
+EXPORT_SYMBOL_GPL(slim_report_absent);
+
+static bool slim_eaddr_equal(struct slim_eaddr *a, struct slim_eaddr *b)
+{
+ return (a->manf_id == b->manf_id &&
+ a->prod_code == b->prod_code &&
+ a->dev_index == b->dev_index &&
+ a->instance == b->instance);
+}
+
+static int slim_match_dev(struct device *dev, void *data)
+{
+ struct slim_eaddr *e_addr = data;
+ struct slim_device *sbdev = to_slim_device(dev);
+
+ return slim_eaddr_equal(&sbdev->e_addr, e_addr);
+}
+
+static struct slim_device *find_slim_device(struct slim_controller *ctrl,
+ struct slim_eaddr *eaddr)
+{
+ struct slim_device *sbdev;
+ struct device *dev;
+
+ dev = device_find_child(ctrl->dev, eaddr, slim_match_dev);
+ if (dev) {
+ sbdev = to_slim_device(dev);
+ return sbdev;
+ }
+
+ return NULL;
+}
+
+/**
+ * slim_get_device() - get handle to a device.
+ *
+ * @ctrl: Controller on which this device will be added/queried
+ * @e_addr: Enumeration address of the device to be queried
+ *
+ * Return: pointer to a device if it has already reported. Creates a new
+ * device and returns pointer to it if the device has not yet enumerated.
+ */
+struct slim_device *slim_get_device(struct slim_controller *ctrl,
+ struct slim_eaddr *e_addr)
+{
+ struct slim_device *sbdev;
+
+ sbdev = find_slim_device(ctrl, e_addr);
+ if (!sbdev) {
+ sbdev = slim_alloc_device(ctrl, e_addr, NULL);
+ if (!sbdev)
+ return ERR_PTR(-ENOMEM);
+ }
+
+ return sbdev;
+}
+EXPORT_SYMBOL_GPL(slim_get_device);
+
+static int slim_device_alloc_laddr(struct slim_device *sbdev,
+ u8 *laddr, bool report_present)
+{
+ struct slim_controller *ctrl = sbdev->ctrl;
+ int ret;
+
+ mutex_lock(&ctrl->lock);
+ if (ctrl->get_laddr) {
+ ret = ctrl->get_laddr(ctrl, &sbdev->e_addr, laddr);
+ if (ret < 0)
+ goto err;
+ } else if (report_present) {
+ ret = ida_simple_get(&ctrl->laddr_ida,
+ 0, SLIM_LA_MANAGER - 1, GFP_KERNEL);
+ if (ret < 0)
+ goto err;
+
+ *laddr = ret;
+ } else {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ if (ctrl->set_laddr) {
+ ret = ctrl->set_laddr(ctrl, &sbdev->e_addr, *laddr);
+ if (ret) {
+ ret = -EINVAL;
+ goto err;
+ }
+ }
+
+ sbdev->laddr = *laddr;
+ sbdev->is_laddr_valid = true;
+
+ slim_device_update_status(sbdev, SLIM_DEVICE_STATUS_UP);
+
+ dev_dbg(ctrl->dev, "setting slimbus l-addr:%x, ea:%x,%x,%x,%x\n",
+ *laddr, sbdev->e_addr.manf_id, sbdev->e_addr.prod_code,
+ sbdev->e_addr.dev_index, sbdev->e_addr.instance);
+
+err:
+ mutex_unlock(&ctrl->lock);
+ return ret;
+
+}
+
+/**
+ * slim_device_report_present() - Report enumerated device.
+ *
+ * @ctrl: Controller with which device is enumerated.
+ * @e_addr: Enumeration address of the device.
+ * @laddr: Return logical address (if valid flag is false)
+ *
+ * Called by controller in response to REPORT_PRESENT. Framework will assign
+ * a logical address to this enumeration address.
+ * Function returns -EXFULL to indicate that all logical addresses are already
+ * taken.
+ */
+int slim_device_report_present(struct slim_controller *ctrl,
+ struct slim_eaddr *e_addr, u8 *laddr)
+{
+ struct slim_device *sbdev;
+ int ret;
+
+ sbdev = slim_get_device(ctrl, e_addr);
+ if (IS_ERR(sbdev))
+ return -ENODEV;
+
+ if (sbdev->is_laddr_valid) {
+ *laddr = sbdev->laddr;
+ return 0;
+ }
+
+ ret = slim_device_alloc_laddr(sbdev, laddr, true);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(slim_device_report_present);
+
+/**
+ * slim_get_logical_addr() - Return the logical address of a slimbus device.
+ *
+ * @sbdev: client handle requesting the address.
+ * @laddr: output buffer to store the address
+ *
+ * Can sleep, -EINVAL is returned in case of invalid parameters,
+ * and -ENXIO is returned if the device with this enumeration address
+ * is not found.
+ */
+int slim_get_logical_addr(struct slim_device *sbdev, u8 *laddr)
+{
+ if (sbdev->is_laddr_valid) {
+ *laddr = sbdev->laddr;
+ return 0;
+ }
+
+ return slim_device_alloc_laddr(sbdev, laddr, false);
+}
+EXPORT_SYMBOL_GPL(slim_get_logical_addr);
+
static void __exit slimbus_exit(void)
{
bus_unregister(&slimbus_bus);
diff --git a/drivers/slimbus/slimbus.h b/drivers/slimbus/slimbus.h
new file mode 100644
index 000000000000..b53319992ad4
--- /dev/null
+++ b/drivers/slimbus/slimbus.h
@@ -0,0 +1,116 @@
+/* Copyright (c) 2011-2017, The Linux Foundation. All rights reserved.
+ *
+ * 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.
+ */
+
+#ifndef _DRIVERS_SLIMBUS_H
+#define _DRIVERS_SLIMBUS_H
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/slimbus.h>
+
+/* Standard values per SLIMbus spec needed by controllers and devices */
+#define SLIM_MAX_CLK_GEAR 10
+#define SLIM_MIN_CLK_GEAR 1
+
+/* Manager's logical address is set to 0xFF per spec */
+#define SLIM_LA_MANAGER 0xFF
+
+/**
+ * struct slim_framer - Represents Slimbus framer.
+ * Every controller may have multiple framers. There is 1 active framer device
+ * responsible for clocking the bus.
+ * Manager is responsible for framer hand-over.
+ * @dev: Driver model representation of the device.
+ * @e_addr: Enumeration address of the framer.
+ * @rootfreq: Root Frequency at which the framer can run. This is maximum
+ * frequency ('clock gear 10') at which the bus can operate.
+ * @superfreq: Superframes per root frequency. Every frame is 6144 bits.
+ */
+struct slim_framer {
+ struct device dev;
+ struct slim_eaddr e_addr;
+ int rootfreq;
+ int superfreq;
+};
+
+#define to_slim_framer(d) container_of(d, struct slim_framer, dev)
+
+/**
+ * struct slim_controller - Controls every instance of SLIMbus
+ * (similar to 'master' on SPI)
+ * @dev: Device interface to this driver
+ * @id: Board-specific number identifier for this controller/bus
+ * @name: Name for this controller
+ * @min_cg: Minimum clock gear supported by this controller (default value: 1)
+ * @max_cg: Maximum clock gear supported by this controller (default value: 10)
+ * @clkgear: Current clock gear in which this bus is running
+ * @laddr_ida: logical address id allocator
+ * @a_framer: Active framer which is clocking the bus managed by this controller
+ * @lock: Mutex protecting controller data structures
+ * @addr: Logical address table
+ * @devices: Slim device list
+ * @tid_idr: tid id allocator
+ * @txn_lock: Lock to protect table of transactions
+ * @set_laddr: Setup logical address at laddr for the slave with elemental
+ * address e_addr. Drivers implementing controller will be expected to
+ * send unicast message to this device with its logical address.
+ * @get_laddr: It is possible that controller needs to set fixed logical
+ * address table and get_laddr can be used in that case so that controller
+ * can do this assignment. Use case is when the master is on the remote
+ * processor side, who is resposible for allocating laddr.
+ *
+ * 'Manager device' is responsible for device management, bandwidth
+ * allocation, channel setup, and port associations per channel.
+ * Device management means Logical address assignment/removal based on
+ * enumeration (report-present, report-absent) of a device.
+ * Bandwidth allocation is done dynamically by the manager based on active
+ * channels on the bus, message-bandwidth requests made by slimbus devices.
+ * Based on current bandwidth usage, manager chooses a frequency to run
+ * the bus at (in steps of 'clock-gear', 1 through 10, each clock gear
+ * representing twice the frequency than the previous gear).
+ * Manager is also responsible for entering (and exiting) low-power-mode
+ * (known as 'clock pause').
+ * Manager can do handover of framer if there are multiple framers on the
+ * bus and a certain usecase warrants using certain framer to avoid keeping
+ * previous framer being powered-on.
+ *
+ * Controller here performs duties of the manager device, and 'interface
+ * device'. Interface device is responsible for monitoring the bus and
+ * reporting information such as loss-of-synchronization, data
+ * slot-collision.
+ */
+struct slim_controller {
+ struct device *dev;
+ unsigned int id;
+ char name[SLIMBUS_NAME_SIZE];
+ int min_cg;
+ int max_cg;
+ int clkgear;
+ struct ida laddr_ida;
+ struct slim_framer *a_framer;
+ struct mutex lock;
+ struct list_head devices;
+ struct idr tid_idr;
+ spinlock_t txn_lock;
+ int (*set_laddr)(struct slim_controller *ctrl,
+ struct slim_eaddr *ea, u8 laddr);
+ int (*get_laddr)(struct slim_controller *ctrl,
+ struct slim_eaddr *ea, u8 *laddr);
+};
+
+int slim_device_report_present(struct slim_controller *ctrl,
+ struct slim_eaddr *e_addr, u8 *laddr);
+void slim_report_absent(struct slim_device *sbdev);
+int slim_register_controller(struct slim_controller *ctrl);
+int slim_unregister_controller(struct slim_controller *ctrl);
+
+#endif /* _LINUX_SLIMBUS_H */
diff --git a/include/linux/slimbus.h b/include/linux/slimbus.h
index 057198216a65..ba3fdf1f5176 100644
--- a/include/linux/slimbus.h
+++ b/include/linux/slimbus.h
@@ -49,6 +49,8 @@ enum slim_device_status {
SLIM_DEVICE_STATUS_RESERVED,
};

+struct slim_controller;
+
/**
* struct slim_device - Slim device handle.
* @dev: Driver model representation of the device.
@@ -65,6 +67,7 @@ struct slim_device {
struct device dev;
struct slim_eaddr e_addr;
struct list_head node;
+ struct slim_controller *ctrl;
enum slim_device_status status;
u8 laddr;
bool is_laddr_valid;
@@ -126,4 +129,8 @@ static inline void slim_set_devicedata(struct slim_device *dev, void *data)
{
dev_set_drvdata(&dev->dev, data);
}
+
+struct slim_device *slim_get_device(struct slim_controller *ctrl,
+ struct slim_eaddr *e_addr);
+int slim_get_logical_addr(struct slim_device *sbdev, u8 *laddr);
#endif /* _LINUX_SLIMBUS_H */
--
2.15.0

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