Date:	Mon, 11 Apr 2011 09:24:24 -0600
From:	mathieu.poirier@...aro.org
To:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:	ohad@...ery.com, mathieu.poirier@...aro.org, lee.jones@...aro.org,
	patches@...aro.org, linus.walleij@...ricsson.com
Subject: [PATCH 1/2] ux500: Adding support for u8500 Hsem functionality V2

From: Mathieu J. Poirier <mathieu.poirier@...aro.org>

This is the second spin on STE's Hsem driver that is implemented
through the hwspinlock scheme.  More specifically:

 More comments have been added in the code.
 Cleanup of included header files.
 One of the original contributor's name corrected.
 Calls to 'pm_runtime_disable'restored.

Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
---
 drivers/hwspinlock/Kconfig      |   23 +++-
 drivers/hwspinlock/Makefile     |    1 +
 drivers/hwspinlock/u8500_hsem.c |  246 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 266 insertions(+), 4 deletions(-)
 create mode 100644 drivers/hwspinlock/u8500_hsem.c

diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
index 1f29bab..9b4f135 100644
--- a/drivers/hwspinlock/Kconfig
+++ b/drivers/hwspinlock/Kconfig
@@ -2,10 +2,11 @@
 # Generic HWSPINLOCK framework
 #
 
-config HWSPINLOCK
-	tristate "Generic Hardware Spinlock framework"
-	depends on ARCH_OMAP4
-	help
+menuconfig HWSPINLOCK
+	bool "Generic Hardware Spinlock framework"
+	depends on ARCH_OMAP4 || ARCH_U8500
+	default n
+	---help---
 	  Say y here to support the generic hardware spinlock framework.
 	  You only need to enable this if you have hardware spinlock module
 	  on your system (usually only relevant if your system has remote slave
@@ -13,6 +14,8 @@ config HWSPINLOCK
 
 	  If unsure, say N.
 
+if HWSPINLOCK
+
 config HWSPINLOCK_OMAP
 	tristate "OMAP Hardware Spinlock device"
 	depends on HWSPINLOCK && ARCH_OMAP4
@@ -21,3 +24,15 @@ config HWSPINLOCK_OMAP
 	  introduced in OMAP4).
 
 	  If unsure, say N.
+
+config HSEM_U8500
+	tristate "STE Hardware Semaphore functionality"
+	depends on HWSPINLOCK && ARCH_U8500
+	help
+	  Say y here to support the STE Hardware Semaphore functionality.  They
+	  provide a synchronisation mechanism for the various processor on the
+	  SoC.
+
+	  If unsure, say N.
+
+endif # HWSPINLOCK
diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
index 5729a3f..93eb64b 100644
--- a/drivers/hwspinlock/Makefile
+++ b/drivers/hwspinlock/Makefile
@@ -4,3 +4,4 @@
 
 obj-$(CONFIG_HWSPINLOCK)		+= hwspinlock_core.o
 obj-$(CONFIG_HWSPINLOCK_OMAP)		+= omap_hwspinlock.o
+obj-$(CONFIG_HSEM_U8500)		+= u8500_hsem.o
diff --git a/drivers/hwspinlock/u8500_hsem.c b/drivers/hwspinlock/u8500_hsem.c
new file mode 100644
index 0000000..d5bedd3
--- /dev/null
+++ b/drivers/hwspinlock/u8500_hsem.c
@@ -0,0 +1,246 @@
+/*
+ * u8500 HWSEM driver
+ *
+ * Copyright (C) 2010-2011 ST-Ericsson
+ *
+ * Implements u8500 semaphore handling for protocol 1, no interrupts.
+ *
+ * Author: Mathieu Poirier <mathieu.poirier@...aro.org>
+ * Heavily borrowed from the work of :
+ *   Simon Que <sque@...com>
+ *   Hari Kanigeri <h-kanigeri2@...com>
+ *   Ohad Ben-Cohen <ohad@...ery.com>
+ *
+ * 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.
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/hwspinlock.h>
+#include <linux/platform_device.h>
+
+#include "hwspinlock_internal.h"
+
+/*
+ * Implementation of STE's HSem protocol 1 without interrutps.
+ * The only masterID we allow is '0x01' to force people to use
+ * HSems for synchronisation between processors rather than processes
+ * on the ARM core.
+ */
+
+#define U8500_MAX_SEMAPHORE		32	/* a total of 32 semaphore */
+#define RESET_SEMAPHORE			(0)	/* free */
+
+/* CPU ID for master running u8500 kernel.
+ * Hswpinlocks should only be used to synchonise operations
+ * between the Cortex A9 core and the other CPUs.  Hence
+ * forcing the masterID to a preset value.
+ */
+#define HSEM_MASTER_ID			0x01
+
+#define HSEM_REGISTER_OFFSET		0x08
+
+#define HSEM_CTRL_REG			0x00
+#define HSEM_ICRALL			0x90
+#define HSEM_PROTOCOL_1			0x01
+
+#define to_u8500_hsem(lock)	\
+	container_of(lock, struct u8500_hsem, lock)
+
+struct u8500_hsem {
+	struct hwspinlock lock;
+	void __iomem *addr;
+};
+
+struct u8500_hsem_state {
+	void __iomem *io_base;		/* Mapped base address */
+};
+
+static int u8500_hsem_trylock(struct hwspinlock *lock)
+{
+	struct u8500_hsem *u8500_lock = to_u8500_hsem(lock);
+
+	writel(HSEM_MASTER_ID, u8500_lock->addr);
+
+	/* get only first 4 bit and compare to masterID.
+	 * if equal, we have the semaphore, otherwise
+	 * someone else has it.
+	 */
+	return (HSEM_MASTER_ID == (0x0F & readl(u8500_lock->addr)));
+}
+
+static void u8500_hsem_unlock(struct hwspinlock *lock)
+{
+	struct u8500_hsem *u8500_lock = to_u8500_hsem(lock);
+
+	/* release the lock by writing 0 to it */
+	writel(RESET_SEMAPHORE, u8500_lock->addr);
+}
+
+/*
+ * u8500: what value is recommended here ?
+ */
+static void u8500_hsem_relax(struct hwspinlock *lock)
+{
+	ndelay(50);
+}
+
+static const struct hwspinlock_ops u8500_hwspinlock_ops = {
+	.trylock	= u8500_hsem_trylock,
+	.unlock		= u8500_hsem_unlock,
+	.relax		= u8500_hsem_relax,
+};
+
+static int __devinit u8500_hsem_probe(struct platform_device *pdev)
+{
+
+	struct u8500_hsem *u8500_lock;
+	struct u8500_hsem_state *state;
+	struct hwspinlock *lock;
+	struct resource *res;
+	void __iomem *io_base;
+	int i, ret;
+	ulong offset, val;
+
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	io_base = ioremap(res->start, resource_size(res));
+	if (!io_base) {
+		ret = -ENOMEM;
+		goto free_state;
+	}
+
+	/* make sure protocol 1 is selected */
+	val = readl(io_base + HSEM_CTRL_REG);
+	writel((val & ~HSEM_PROTOCOL_1), io_base + HSEM_CTRL_REG);
+
+	/* clear all interrupts */
+	writel(0xFFFF, io_base + HSEM_ICRALL);
+
+	state->io_base = io_base;
+
+	platform_set_drvdata(pdev, state);
+
+	/*
+	 * no pm needed for HSem but required to comply
+	 * with hwspilock core.
+	 */
+	pm_runtime_enable(&pdev->dev);
+
+	offset = HSEM_REGISTER_OFFSET;
+
+	for (i = 0; i < U8500_MAX_SEMAPHORE; i++) {
+		u8500_lock = kzalloc(sizeof(*u8500_lock), GFP_KERNEL);
+		if (!u8500_lock) {
+			ret = -ENOMEM;
+			goto free_locks;
+		}
+
+		u8500_lock->lock.dev = &pdev->dev;
+		u8500_lock->lock.owner = THIS_MODULE;
+		u8500_lock->lock.id = i;
+		u8500_lock->lock.ops = &u8500_hwspinlock_ops;
+		u8500_lock->addr = io_base + offset + sizeof(u32) * i;
+
+		ret = hwspin_lock_register(&u8500_lock->lock);
+		if (ret) {
+			kfree(u8500_lock);
+			goto free_locks;
+		}
+	}
+
+	return 0;
+
+free_locks:
+	while (--i >= 0) {
+		lock = hwspin_lock_unregister(i);
+		/* this should't happen, but let's give our best effort */
+		if (!lock) {
+			dev_err(&pdev->dev, "%s: cleanups failed\n", __func__);
+			continue;
+		}
+		u8500_lock = to_u8500_hsem(lock);
+		kfree(u8500_lock);
+	}
+
+	pm_runtime_disable(&pdev->dev);
+	iounmap(io_base);
+free_state:
+	kfree(state);
+	return ret;
+}
+
+static int u8500_hsem_remove(struct platform_device *pdev)
+{
+	struct u8500_hsem_state *state = platform_get_drvdata(pdev);
+	struct hwspinlock *lock;
+	struct u8500_hsem *u8500_lock;
+	void __iomem *io_base;
+	int i;
+
+	io_base = state->io_base;
+
+	/* clear all interrupts */
+	writel(0xFFFF, io_base + HSEM_ICRALL);
+
+	for (i = 0; i < U8500_MAX_SEMAPHORE; i++) {
+		lock = hwspin_lock_unregister(i);
+		/* this shouldn't happen at this point. if it does, at least
+		 * don't continue with the remove */
+		if (!lock) {
+			dev_err(&pdev->dev, "%s: failed on %d\n", __func__, i);
+			return -EBUSY;
+		}
+
+		u8500_lock = to_u8500_hsem(lock);
+		kfree(u8500_lock);
+	}
+
+	pm_runtime_disable(&pdev->dev);
+	iounmap(io_base);
+	kfree(state);
+
+	return 0;
+}
+
+static struct platform_driver u8500_hsem_driver = {
+	.probe		= u8500_hsem_probe,
+	.remove		= u8500_hsem_remove,
+	.driver		= {
+		.name	= "u8500_hsem",
+	},
+};
+
+static int __init u8500_hsem_init(void)
+{
+	return platform_driver_register(&u8500_hsem_driver);
+}
+/* board init code might need to reserve hwspinlocks for predefined purposes */
+postcore_initcall(u8500_hsem_init);
+
+static void __exit u8500_hsem_exit(void)
+{
+	platform_driver_unregister(&u8500_hsem_driver);
+}
+module_exit(u8500_hsem_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware Semaphore driver for u8500");
+MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@...aro.org");
-- 
1.7.1

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