hwspinlock/u8500: add hwspinlock driver

Add hwspinlock driver for U8500's Hsem hardware.

At this point only HSem's protocol 1 is used (i.e. no interrupts).

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
[ohad@wizery.com: adopt recent hwspin_lock_{un}register API changes]
[ohad@wizery.com: set the owner member of the driver]
[ohad@wizery.com: mark ->remove() function as __devexit]
[ohad@wizery.com: write commit log]
[ohad@wizery.com: small cleanups]
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>

drivers/hwspinlock/Kconfig

@@ -18,4 +18,15 @@ config HWSPINLOCK_OMAP
 
 	  If unsure, say N.
 
+config HSEM_U8500
+	tristate "STE Hardware Semaphore functionality"
+	depends on ARCH_U8500
+	select HWSPINLOCK
+	help
+	  Say y here to support the STE Hardware Semaphore functionality, which
+	  provides a synchronisation mechanism for the various processor on the
+	  SoC.
+
+	  If unsure, say N.
+
 endmenu

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

drivers/hwspinlock/u8500_hsem.c

@@ -0,0 +1,198 @@
+/*
+ * u8500 HWSEM driver
+ *
+ * Copyright (C) 2010-2011 ST-Ericsson
+ *
+ * Implements u8500 semaphore handling for protocol 1, no interrupts.
+ *
+ * Author: Mathieu Poirier <mathieu.poirier@linaro.org>
+ * Heavily borrowed from the work of :
+ *   Simon Que <sque@ti.com>
+ *   Hari Kanigeri <h-kanigeri2@ti.com>
+ *   Ohad Ben-Cohen <ohad@wizery.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
+
+static int u8500_hsem_trylock(struct hwspinlock *lock)
+{
+	void __iomem *lock_addr = lock->priv;
+
+	writel(HSEM_MASTER_ID, 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(lock_addr)));
+}
+
+static void u8500_hsem_unlock(struct hwspinlock *lock)
+{
+	void __iomem *lock_addr = lock->priv;
+
+	/* release the lock by writing 0 to it */
+	writel(RESET_SEMAPHORE, 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 hwspinlock_pdata *pdata = pdev->dev.platform_data;
+	struct hwspinlock_device *bank;
+	struct hwspinlock *hwlock;
+	struct resource *res;
+	void __iomem *io_base;
+	int i, ret, num_locks = U8500_MAX_SEMAPHORE;
+	ulong val;
+
+	if (!pdata)
+		return -ENODEV;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	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);
+
+	bank = kzalloc(sizeof(*bank) + num_locks * sizeof(*hwlock), GFP_KERNEL);
+	if (!bank) {
+		ret = -ENOMEM;
+		goto iounmap_base;
+	}
+
+	platform_set_drvdata(pdev, bank);
+
+	for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
+		hwlock->priv = io_base + HSEM_REGISTER_OFFSET + sizeof(u32) * i;
+
+	/* no pm needed for HSem but required to comply with hwspilock core */
+	pm_runtime_enable(&pdev->dev);
+
+	ret = hwspin_lock_register(bank, &pdev->dev, &u8500_hwspinlock_ops,
+						pdata->base_id, num_locks);
+	if (ret)
+		goto reg_fail;
+
+	return 0;
+
+reg_fail:
+	pm_runtime_disable(&pdev->dev);
+	kfree(bank);
+iounmap_base:
+	iounmap(io_base);
+	return ret;
+}
+
+static int __devexit u8500_hsem_remove(struct platform_device *pdev)
+{
+	struct hwspinlock_device *bank = platform_get_drvdata(pdev);
+	void __iomem *io_base = bank->lock[0].priv - HSEM_REGISTER_OFFSET;
+	int ret;
+
+	/* clear all interrupts */
+	writel(0xFFFF, io_base + HSEM_ICRALL);
+
+	ret = hwspin_lock_unregister(bank);
+	if (ret) {
+		dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
+		return ret;
+	}
+
+	pm_runtime_disable(&pdev->dev);
+	iounmap(io_base);
+	kfree(bank);
+
+	return 0;
+}
+
+static struct platform_driver u8500_hsem_driver = {
+	.probe		= u8500_hsem_probe,
+	.remove		= __devexit_p(u8500_hsem_remove),
+	.driver		= {
+		.name	= "u8500_hsem",
+		.owner	= THIS_MODULE,
+	},
+};
+
+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 Spinlock driver for u8500");
+MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");