[PATCH 1/6] platform-drivers: msm: add single-wire serial bus interface (SSBI) driver

[David Brown]

From: Kenneth Heitke <kheitke@xxxxxxxxxxxxxx>

SSBI is the Qualcomm single-wire serial bus interface used to connect
the MSM devices to the PMIC and other devices.

Since SSBI only supports a single slave, the driver gets the name of the
slave device passed in from the board file through the master device's
platform data.

SSBI registers pretty early (postcore), so that the PMIC can come up
before the board init. This is useful if the board init requires the
use of gpios that are connected through the PMIC.

Based on a patch by Dima Zavin <dima@xxxxxxxxxxx> that can be found at:
http://android.git.kernel.org/?p=kernel/msm.git;a=commitdiff;h=eb060bac4

This patch adds PMIC Arbiter support for the MSM8660. The PMIC Arbiter
is a hardware wrapper around the SSBI 2.0 controller that is designed to
overcome concurrency issues and security limitations.  A controller_type
field is added to the platform data to specify the type of the SSBI
controller (1.0, 2.0, or PMIC Arbiter).

[davidb@xxxxxxxxxxxxxx:
 I've moved this driver into drivers/ssbi/ and added an include for
 linux/module.h so that it will compile]

Signed-off-by: Kenneth Heitke <kheitke@xxxxxxxxxxxxxx>
Signed-off-by: David Brown <davidb@xxxxxxxxxxxxxx>
---
 drivers/Kconfig          |   2 +
 drivers/Makefile         |   1 +
 drivers/ssbi/Kconfig     |  17 ++
 drivers/ssbi/Makefile    |   4 +
 drivers/ssbi/ssbi.c      | 397 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/msm_ssbi.h |  49 ++++++
 6 files changed, 470 insertions(+)
 create mode 100644 drivers/ssbi/Kconfig
 create mode 100644 drivers/ssbi/Makefile
 create mode 100644 drivers/ssbi/ssbi.c
 create mode 100644 include/linux/msm_ssbi.h

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 202fa6d..78a956e 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -52,6 +52,8 @@ source "drivers/i2c/Kconfig"
 
 source "drivers/spi/Kconfig"
 
+source "drivers/ssbi/Kconfig"
+
 source "drivers/hsi/Kconfig"
 
 source "drivers/pps/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index dce39a9..778821b 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -114,6 +114,7 @@ obj-y				+= firmware/
 obj-$(CONFIG_CRYPTO)		+= crypto/
 obj-$(CONFIG_SUPERH)		+= sh/
 obj-$(CONFIG_ARCH_SHMOBILE)	+= sh/
+obj-$(CONFIG_MSM_SSBI)		+= ssbi/
 ifndef CONFIG_ARCH_USES_GETTIMEOFFSET
 obj-y				+= clocksource/
 endif
diff --git a/drivers/ssbi/Kconfig b/drivers/ssbi/Kconfig
new file mode 100644
index 0000000..b667e62
--- /dev/null
+++ b/drivers/ssbi/Kconfig
@@ -0,0 +1,17 @@
+#
+# MSM SSBI bus support
+#
+
+menu "Qualcomm MSM SSBI bus support"
+	depends on ARCH_MSM
+
+config MSM_SSBI
+	bool "Qualcomm Single-wire Serial Bus Interface (SSBI)"
+	help
+	  If you say yes to this option, support will be included for the
+	  built-in SSBI interface on Qualcomm MSM family processors.
+
+	  This is required for communicating with Qualcomm PMICs and
+	  other devices that have the SSBI interface.
+
+endmenu
diff --git a/drivers/ssbi/Makefile b/drivers/ssbi/Makefile
new file mode 100644
index 0000000..ea8c1e4
--- /dev/null
+++ b/drivers/ssbi/Makefile
@@ -0,0 +1,4 @@
+#
+# Makefile for the MSM specific device drivers.
+#
+obj-$(CONFIG_MSM_SSBI) += ssbi.o
diff --git a/drivers/ssbi/ssbi.c b/drivers/ssbi/ssbi.c
new file mode 100644
index 0000000..8b0b10d
--- /dev/null
+++ b/drivers/ssbi/ssbi.c
@@ -0,0 +1,397 @@
+/* Copyright (c) 2009-2011, Code Aurora Forum. All rights reserved.
+ * Copyright (c) 2010, Google Inc.
+ *
+ * Original authors: Code Aurora Forum
+ *
+ * Author: Dima Zavin <dima@xxxxxxxxxxx>
+ *  - Largely rewritten from original to not be an i2c driver.
+ *
+ * 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.
+ */
+
+#define pr_fmt(fmt) "%s: " fmt, __func__
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/msm_ssbi.h>
+#include <linux/module.h>
+
+/* SSBI 2.0 controller registers */
+#define SSBI2_CMD			0x0008
+#define SSBI2_RD			0x0010
+#define SSBI2_STATUS			0x0014
+#define SSBI2_MODE2			0x001C
+
+/* SSBI_CMD fields */
+#define SSBI_CMD_RDWRN			(1 << 24)
+
+/* SSBI_STATUS fields */
+#define SSBI_STATUS_RD_READY		(1 << 2)
+#define SSBI_STATUS_READY		(1 << 1)
+#define SSBI_STATUS_MCHN_BUSY		(1 << 0)
+
+/* SSBI_MODE2 fields */
+#define SSBI_MODE2_REG_ADDR_15_8_SHFT	0x04
+#define SSBI_MODE2_REG_ADDR_15_8_MASK	(0x7f << SSBI_MODE2_REG_ADDR_15_8_SHFT)
+
+#define SET_SSBI_MODE2_REG_ADDR_15_8(MD, AD) \
+	(((MD) & 0x0F) | ((((AD) >> 8) << SSBI_MODE2_REG_ADDR_15_8_SHFT) & \
+	SSBI_MODE2_REG_ADDR_15_8_MASK))
+
+/* SSBI PMIC Arbiter command registers */
+#define SSBI_PA_CMD			0x0000
+#define SSBI_PA_RD_STATUS		0x0004
+
+/* SSBI_PA_CMD fields */
+#define SSBI_PA_CMD_RDWRN		(1 << 24)
+#define SSBI_PA_CMD_ADDR_MASK		0x7fff /* REG_ADDR_7_0, REG_ADDR_8_14*/
+
+/* SSBI_PA_RD_STATUS fields */
+#define SSBI_PA_RD_STATUS_TRANS_DONE	(1 << 27)
+#define SSBI_PA_RD_STATUS_TRANS_DENIED	(1 << 26)
+
+#define SSBI_TIMEOUT_US			100
+
+struct msm_ssbi {
+	struct device		*dev;
+	struct device		*slave;
+	void __iomem		*base;
+	spinlock_t		lock;
+	enum msm_ssbi_controller_type controller_type;
+	int (*read)(struct msm_ssbi *, u16 addr, u8 *buf, int len);
+	int (*write)(struct msm_ssbi *, u16 addr, u8 *buf, int len);
+};
+
+#define to_msm_ssbi(dev)	platform_get_drvdata(to_platform_device(dev))
+
+static inline u32 ssbi_readl(struct msm_ssbi *ssbi, u32 reg)
+{
+	return readl(ssbi->base + reg);
+}
+
+static inline void ssbi_writel(struct msm_ssbi *ssbi, u32 val, u32 reg)
+{
+	writel(val, ssbi->base + reg);
+}
+
+static int ssbi_wait_mask(struct msm_ssbi *ssbi, u32 set_mask, u32 clr_mask)
+{
+	u32 timeout = SSBI_TIMEOUT_US;
+	u32 val;
+
+	while (timeout--) {
+		val = ssbi_readl(ssbi, SSBI2_STATUS);
+		if (((val & set_mask) == set_mask) && ((val & clr_mask) == 0))
+			return 0;
+		udelay(1);
+	}
+
+	dev_err(ssbi->dev, "%s: timeout (status %x set_mask %x clr_mask %x)\n",
+		__func__, ssbi_readl(ssbi, SSBI2_STATUS), set_mask, clr_mask);
+	return -ETIMEDOUT;
+}
+
+static int
+msm_ssbi_read_bytes(struct msm_ssbi *ssbi, u16 addr, u8 *buf, int len)
+{
+	u32 cmd = SSBI_CMD_RDWRN | ((addr & 0xff) << 16);
+	int ret = 0;
+
+	if (ssbi->controller_type == MSM_SBI_CTRL_SSBI2) {
+		u32 mode2 = ssbi_readl(ssbi, SSBI2_MODE2);
+		mode2 = SET_SSBI_MODE2_REG_ADDR_15_8(mode2, addr);
+		ssbi_writel(ssbi, mode2, SSBI2_MODE2);
+	}
+
+	while (len) {
+		ret = ssbi_wait_mask(ssbi, SSBI_STATUS_READY, 0);
+		if (ret)
+			goto err;
+
+		ssbi_writel(ssbi, cmd, SSBI2_CMD);
+		ret = ssbi_wait_mask(ssbi, SSBI_STATUS_RD_READY, 0);
+		if (ret)
+			goto err;
+		*buf++ = ssbi_readl(ssbi, SSBI2_RD) & 0xff;
+		len--;
+	}
+
+err:
+	return ret;
+}
+
+static int
+msm_ssbi_write_bytes(struct msm_ssbi *ssbi, u16 addr, u8 *buf, int len)
+{
+	int ret = 0;
+
+	if (ssbi->controller_type == MSM_SBI_CTRL_SSBI2) {
+		u32 mode2 = ssbi_readl(ssbi, SSBI2_MODE2);
+		mode2 = SET_SSBI_MODE2_REG_ADDR_15_8(mode2, addr);
+		ssbi_writel(ssbi, mode2, SSBI2_MODE2);
+	}
+
+	while (len) {
+		ret = ssbi_wait_mask(ssbi, SSBI_STATUS_READY, 0);
+		if (ret)
+			goto err;
+
+		ssbi_writel(ssbi, ((addr & 0xff) << 16) | *buf, SSBI2_CMD);
+		ret = ssbi_wait_mask(ssbi, 0, SSBI_STATUS_MCHN_BUSY);
+		if (ret)
+			goto err;
+		buf++;
+		len--;
+	}
+
+err:
+	return ret;
+}
+
+static inline int
+msm_ssbi_pa_transfer(struct msm_ssbi *ssbi, u32 cmd, u8 *data)
+{
+	u32 timeout = SSBI_TIMEOUT_US;
+	u32 rd_status = 0;
+
+	ssbi_writel(ssbi, cmd, SSBI_PA_CMD);
+
+	while (timeout--) {
+		rd_status = ssbi_readl(ssbi, SSBI_PA_RD_STATUS);
+
+		if (rd_status & SSBI_PA_RD_STATUS_TRANS_DENIED) {
+			dev_err(ssbi->dev, "%s: transaction denied (0x%x)\n",
+					__func__, rd_status);
+			return -EPERM;
+		}
+
+		if (rd_status & SSBI_PA_RD_STATUS_TRANS_DONE) {
+			if (data)
+				*data = rd_status & 0xff;
+			return 0;
+		}
+		udelay(1);
+	}
+
+	dev_err(ssbi->dev, "%s: timeout, status 0x%x\n", __func__, rd_status);
+	return -ETIMEDOUT;
+}
+
+static int
+msm_ssbi_pa_read_bytes(struct msm_ssbi *ssbi, u16 addr, u8 *buf, int len)
+{
+	u32 cmd;
+	int ret = 0;
+
+	cmd = SSBI_PA_CMD_RDWRN | (addr & SSBI_PA_CMD_ADDR_MASK) << 8;
+
+	while (len) {
+		ret = msm_ssbi_pa_transfer(ssbi, cmd, buf);
+		if (ret)
+			goto err;
+		buf++;
+		len--;
+	}
+
+err:
+	return ret;
+}
+
+static int
+msm_ssbi_pa_write_bytes(struct msm_ssbi *ssbi, u16 addr, u8 *buf, int len)
+{
+	u32 cmd;
+	int ret = 0;
+
+	while (len) {
+		cmd = (addr & SSBI_PA_CMD_ADDR_MASK) << 8 | *buf;
+		ret = msm_ssbi_pa_transfer(ssbi, cmd, NULL);
+		if (ret)
+			goto err;
+		buf++;
+		len--;
+	}
+
+err:
+	return ret;
+}
+
+int msm_ssbi_read(struct device *dev, u16 addr, u8 *buf, int len)
+{
+	struct msm_ssbi *ssbi = to_msm_ssbi(dev);
+	unsigned long flags;
+	int ret;
+
+	if (ssbi->dev != dev)
+		return -ENXIO;
+
+	spin_lock_irqsave(&ssbi->lock, flags);
+	ret = ssbi->read(ssbi, addr, buf, len);
+	spin_unlock_irqrestore(&ssbi->lock, flags);
+
+	return ret;
+}
+EXPORT_SYMBOL(msm_ssbi_read);
+
+int msm_ssbi_write(struct device *dev, u16 addr, u8 *buf, int len)
+{
+	struct msm_ssbi *ssbi = to_msm_ssbi(dev);
+	unsigned long flags;
+	int ret;
+
+	if (ssbi->dev != dev)
+		return -ENXIO;
+
+	spin_lock_irqsave(&ssbi->lock, flags);
+	ret = ssbi->write(ssbi, addr, buf, len);
+	spin_unlock_irqrestore(&ssbi->lock, flags);
+
+	return ret;
+}
+EXPORT_SYMBOL(msm_ssbi_write);
+
+static int msm_ssbi_add_slave(struct msm_ssbi *ssbi,
+				const struct msm_ssbi_slave_info *slave)
+{
+	struct platform_device *slave_pdev;
+	int ret;
+
+	if (ssbi->slave) {
+		pr_err("slave already attached??\n");
+		return -EBUSY;
+	}
+
+	slave_pdev = platform_device_alloc(slave->name, -1);
+	if (!slave_pdev) {
+		pr_err("cannot allocate pdev for slave '%s'", slave->name);
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	slave_pdev->dev.parent = ssbi->dev;
+	slave_pdev->dev.platform_data = slave->platform_data;
+
+	ret = platform_device_add(slave_pdev);
+	if (ret) {
+		pr_err("cannot add slave platform device for '%s'\n",
+				slave->name);
+		goto err;
+	}
+
+	ssbi->slave = &slave_pdev->dev;
+	return 0;
+
+err:
+	if (slave_pdev)
+		platform_device_put(slave_pdev);
+	return ret;
+}
+
+static int msm_ssbi_probe(struct platform_device *pdev)
+{
+	const struct msm_ssbi_platform_data *pdata = pdev->dev.platform_data;
+	struct resource *mem_res;
+	struct msm_ssbi *ssbi;
+	int ret = 0;
+
+	if (!pdata) {
+		pr_err("missing platform data\n");
+		return -EINVAL;
+	}
+
+	pr_debug("%s\n", pdata->slave.name);
+
+	ssbi = kzalloc(sizeof(struct msm_ssbi), GFP_KERNEL);
+	if (!ssbi) {
+		pr_err("can not allocate ssbi_data\n");
+		return -ENOMEM;
+	}
+
+	mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem_res) {
+		pr_err("missing mem resource\n");
+		ret = -EINVAL;
+		goto err_get_mem_res;
+	}
+
+	ssbi->base = ioremap(mem_res->start, resource_size(mem_res));
+	if (!ssbi->base) {
+		pr_err("ioremap of 0x%p failed\n", (void *)mem_res->start);
+		ret = -EINVAL;
+		goto err_ioremap;
+	}
+	ssbi->dev = &pdev->dev;
+	platform_set_drvdata(pdev, ssbi);
+
+	ssbi->controller_type = pdata->controller_type;
+	if (ssbi->controller_type == MSM_SBI_CTRL_PMIC_ARBITER) {
+		ssbi->read = msm_ssbi_pa_read_bytes;
+		ssbi->write = msm_ssbi_pa_write_bytes;
+	} else {
+		ssbi->read = msm_ssbi_read_bytes;
+		ssbi->write = msm_ssbi_write_bytes;
+	}
+
+	spin_lock_init(&ssbi->lock);
+
+	ret = msm_ssbi_add_slave(ssbi, &pdata->slave);
+	if (ret)
+		goto err_ssbi_add_slave;
+
+	return 0;
+
+err_ssbi_add_slave:
+	platform_set_drvdata(pdev, NULL);
+	iounmap(ssbi->base);
+err_ioremap:
+err_get_mem_res:
+	kfree(ssbi);
+	return ret;
+}
+
+static int msm_ssbi_remove(struct platform_device *pdev)
+{
+	struct msm_ssbi *ssbi = platform_get_drvdata(pdev);
+
+	platform_set_drvdata(pdev, NULL);
+	iounmap(ssbi->base);
+	kfree(ssbi);
+	return 0;
+}
+
+static struct platform_driver msm_ssbi_driver = {
+	.probe		= msm_ssbi_probe,
+	.remove		= __exit_p(msm_ssbi_remove),
+	.driver		= {
+		.name	= "msm_ssbi",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init msm_ssbi_init(void)
+{
+	return platform_driver_register(&msm_ssbi_driver);
+}
+postcore_initcall(msm_ssbi_init);
+
+static void __exit msm_ssbi_exit(void)
+{
+	platform_driver_unregister(&msm_ssbi_driver);
+}
+module_exit(msm_ssbi_exit)
+
+MODULE_LICENSE("GPL v2");
+MODULE_VERSION("1.0");
+MODULE_ALIAS("platform:msm_ssbi");
+MODULE_AUTHOR("Dima Zavin <dima@xxxxxxxxxxx>");
diff --git a/include/linux/msm_ssbi.h b/include/linux/msm_ssbi.h
new file mode 100644
index 0000000..cfa47df
--- /dev/null
+++ b/include/linux/msm_ssbi.h
@@ -0,0 +1,49 @@
+/* Copyright (C) 2010 Google, Inc.
+ * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
+ * Author: Dima Zavin <dima@xxxxxxxxxxx>
+ *
+ * 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 _LINUX_MSM_SSBI_H
+#define _LINUX_MSM_SSBI_H
+
+#include <linux/types.h>
+
+struct msm_ssbi_slave_info {
+	const char	*name;
+	void		*platform_data;
+};
+
+enum msm_ssbi_controller_type {
+	MSM_SBI_CTRL_SSBI = 0,
+	MSM_SBI_CTRL_SSBI2,
+	MSM_SBI_CTRL_PMIC_ARBITER,
+};
+
+struct msm_ssbi_platform_data {
+	struct msm_ssbi_slave_info	slave;
+	enum msm_ssbi_controller_type controller_type;
+};
+
+#ifdef CONFIG_MSM_SSBI
+int msm_ssbi_write(struct device *dev, u16 addr, u8 *buf, int len);
+int msm_ssbi_read(struct device *dev, u16 addr, u8 *buf, int len);
+#else
+static inline int msm_ssbi_write(struct device *dev, u16 addr, u8 *buf, int len)
+{
+	return -ENXIO;
+}
+static inline int msm_ssbi_read(struct device *dev, u16 addr, u8 *buf, int len)
+{
+	return -ENXIO;
+}
+#endif
+#endif
-- 
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