w1: master: tegra_w1: Add initial Tegra W1 master driver

Initial implementation of W1 master driver for Tegra SoCs.
Tested with DS2781 slave driver.

Change-Id: I6cda1ea152d25a789ae6cdca96b710da72884033
Signed-off-by: Andrei Warkentin <andreiw@motorola.com>

3 files changed, 499 insertions, 0 deletions

diff --git a/drivers/w1/masters/Kconfig b/drivers/w1/masters/Kconfig
index 979d6eed9a0f..dd278e51ed88 100644
--- a/drivers/w1/masters/Kconfig
+++ b/drivers/w1/masters/Kconfig
@@ -58,6 +58,13 @@ config W1_MASTER_GPIO
 	  This support is also available as a module.  If so, the module
 	  will be called w1-gpio.
 
+config W1_MASTER_TEGRA
+	tristate "NVidia Tegra SoC 1-wire busmaster"
+	depends on ARCH_TEGRA
+	help
+	  Say Y here if you want to communicate with your 1-wire devices using
+	  the NVidia Tegra SoC one-wire interfaces.
+
 config HDQ_MASTER_OMAP
 	tristate "OMAP HDQ driver"
 	depends on SOC_OMAP2430 || ARCH_OMAP3
diff --git a/drivers/w1/masters/Makefile b/drivers/w1/masters/Makefile
index c5a3e96fcbab..41c5d28e60e7 100644
--- a/drivers/w1/masters/Makefile
+++ b/drivers/w1/masters/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_W1_MASTER_MXC)		+= mxc_w1.o
 obj-$(CONFIG_W1_MASTER_DS1WM)		+= ds1wm.o
 obj-$(CONFIG_W1_MASTER_GPIO)		+= w1-gpio.o
 obj-$(CONFIG_HDQ_MASTER_OMAP)		+= omap_hdq.o
+obj-$(CONFIG_W1_MASTER_TEGRA)		+= tegra_w1.o
diff --git a/drivers/w1/masters/tegra_w1.c b/drivers/w1/masters/tegra_w1.c
new file mode 100644
index 000000000000..9443c4b1dbc6
--- /dev/null
+++ b/drivers/w1/masters/tegra_w1.c
@@ -0,0 +1,491 @@
+/*
+ * drivers/w1/masters/tegra-w1.c
+ *
+ * W1 master driver for internal OWR controllers in NVIDIA Tegra SoCs.
+ *
+ * Copyright (C) 2010 Motorola, Inc
+ * Author: Andrei Warkentin <andreiw@motorola.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+
+#include <mach/w1.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+#include "../w1_log.h"
+
+#define DRIVER_NAME "tegra_w1"
+
+/* OWR_CONTROL_0 is the main control register, and should be configured
+   last after configuring all other settings. */
+#define OWR_CONTROL          (0x0)
+#define OC_RD_BIT            (1 << 31)
+#define OC_WR0_BIT           (1 << 30)
+#define OC_RD_SCLK_SHIFT     (23)
+#define OC_RD_SCLK_MASK      (0xF)
+#define OC_P_SCLK_SHIFT      (15)
+#define OC_P_SCLK_MASK       (0xFF)
+#define OC_BIT_XMODE         (1 << 2)
+#define OC_GO                (1 << 0)
+
+/* OWR_WR_RD_TCTL_0 controls read/write timings. */
+#define OWR_WR_RD_TCTL       (0xc)
+#define ORWT_TSU_SHIFT       (28)
+#define ORWT_TSU_MASK        (0x3)
+#define ORWT_TRELEASE_SHIFT  (22)
+#define ORWT_TRELEASE_MASK   (0x3F)
+#define ORWT_TRDV_SHIFT      (18)
+#define ORWT_TRDV_MASK       (0xF)
+#define ORWT_TLOW0_SHIFT     (11)
+#define ORWT_TLOW0_MASK      (0x7F)
+#define ORWT_TLOW1_SHIFT     (7)
+#define ORWT_TLOW1_MASK      (0xF)
+#define ORWT_TSLOT_SHIFT     (0)
+#define ORWT_TSLOT_MASK      (0x7F)
+
+/* OWR_RST_PRES_TCTL_0 controls reset presence timings. */
+#define OWR_RST_PRES_TCTL    (0x10)
+#define ORPT_TPDL_SHIFT      (24)
+#define ORPT_TPDL_MASK       (0xFF)
+#define ORPT_TPDH_SHIFT      (18)
+#define ORPT_TPDH_MASK       (0x3F)
+#define ORPT_TRSTL_SHIFT     (9)
+#define ORPT_TRSTL_MASK      (0x1FF)
+#define ORPT_TRSTH_SHIFT     (0)
+#define ORPT_TRSTH_MASK      (0x1FF)
+
+/* OWR_INTR_MASK_0 stores the masks for the interrupts. */
+#define OWR_INTR_MASK         (0x24)
+#define OI_BIT_XFER_DONE      (1 << 13)
+#define OI_PRESENCE_DONE      (1 << 5)
+#define OI_PRESENCE_ERR       (1 << 0)
+
+/* OWR_INTR_STATUS_0 is the interrupt status register. */
+#define OWR_INTR_STATUS       (0x28)
+
+/* OWR_STATUS_0 is the status register. */
+#define OWR_STATUS            (0x34)
+#define OS_READ_BIT_SHIFT     (23)
+#define OS_RDY                (1 << 0)
+
+/* Transfer_completion wait time. */
+#define BIT_XFER_COMPLETION_TIMEOUT_MSEC (5000)
+
+/* Errors in the interrupt status register for bit
+   transfers. */
+#define BIT_XFER_ERRORS (OI_PRESENCE_ERR)
+
+/* OWR requires 1MHz clock. This value is in Herz. */
+#define OWR_CLOCK (1000000)
+
+#define W1_ERR(format, ...) \
+	printk(KERN_ERR "(%s: line %d) " format, \
+	__func__, __LINE__, ## __VA_ARGS__)
+
+struct tegra_device {
+	bool ready;
+	struct w1_bus_master bus_master;
+	struct clk *clk;
+	void __iomem *ioaddr;
+	struct mutex mutex;
+	spinlock_t spinlock;
+	struct completion *transfer_completion;
+	unsigned long intr_status;
+	struct tegra_w1_timings *timings;
+};
+
+/* If debug_print & DEBUG_PRESENCE, print whether slaves detected
+   or not in reset_bus. */
+#define DEBUG_PRESENCE (0x1)
+
+/* If debug_print & DEBUG_TIMEOUT, print whether timeouts on waiting
+   for device interrupts occurs. */
+#define DEBUG_TIMEOUT (0x2)
+
+static uint32_t debug_print;
+module_param_named(debug, debug_print, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debugging output commands:\n"
+		 "\tbit 0 - log reset_bus presence detects\n"
+		 "\tbit 1 - log interrupt timeouts\n");
+
+/* Reads the OWR register specified by base offset in 'reg'. */
+static inline unsigned long w1_readl(struct tegra_device *dev,
+				     unsigned long reg)
+{
+	return readl(dev->ioaddr + reg);
+}
+
+/* Writes 'val' into the OWR registers specified by base offset in 'reg'. */
+static inline void w1_writel(struct tegra_device *dev, unsigned long val,
+			     unsigned long reg)
+{
+	writel(val, dev->ioaddr + reg);
+}
+
+/* Sets interrupt mask the device. */
+static inline void w1_imask(struct tegra_device *dev, unsigned long mask)
+{
+	w1_writel(dev, mask, OWR_INTR_MASK);
+}
+
+/* Waits for completion of a bit transfer, checks intr_status against
+   BIT_XFER_ERRORS and an additional provided bit mask. */
+static inline int w1_wait(struct tegra_device *dev, unsigned long mask)
+{
+	int ret;
+	unsigned long irq_flags;
+	unsigned long intr_status;
+
+	ret = wait_for_completion_timeout(dev->transfer_completion,
+		msecs_to_jiffies(BIT_XFER_COMPLETION_TIMEOUT_MSEC));
+
+	if (unlikely(!ret)) {
+		if (debug_print & DEBUG_TIMEOUT)
+			W1_ERR("timeout\n");
+		return -ETIME;
+	}
+
+	spin_lock_irqsave(&dev->spinlock, irq_flags);
+	intr_status = dev->intr_status;
+	dev->intr_status = 0;
+	spin_unlock_irqrestore(&dev->spinlock, irq_flags);
+
+	if (unlikely(intr_status & BIT_XFER_ERRORS ||
+		     !(intr_status & mask)))
+		return -EIO;
+	return 0;
+}
+
+/* Programs timing registers, and puts the device into a known state.
+   Interrupts are safe to enable past this point. */
+static int w1_setup(struct tegra_device *dev)
+{
+	unsigned long value;
+	clk_enable(dev->clk);
+
+	value =
+		((dev->timings->tslot & ORWT_TSLOT_MASK) << ORWT_TSLOT_SHIFT) |
+		((dev->timings->tlow1 & ORWT_TLOW1_MASK) << ORWT_TLOW1_SHIFT) |
+		((dev->timings->tlow0 & ORWT_TLOW0_MASK) << ORWT_TLOW0_SHIFT) |
+		((dev->timings->trdv & ORWT_TRDV_MASK) << ORWT_TRDV_SHIFT) |
+		((dev->timings->trelease & ORWT_TRELEASE_MASK) <<
+		 ORWT_TRELEASE_SHIFT) |
+		((dev->timings->tsu & ORWT_TSU_MASK) << ORWT_TSU_SHIFT);
+	w1_writel(dev, value, OWR_WR_RD_TCTL);
+
+	value =
+		((dev->timings->trsth & ORPT_TRSTH_MASK) << ORPT_TRSTH_SHIFT) |
+		((dev->timings->trstl & ORPT_TRSTL_MASK) << ORPT_TRSTL_SHIFT) |
+		((dev->timings->tpdh & ORPT_TPDH_MASK) << ORPT_TPDH_SHIFT) |
+		((dev->timings->tpdl & ORPT_TPDL_MASK) << ORPT_TPDL_SHIFT);
+	w1_writel(dev, value, OWR_RST_PRES_TCTL);
+
+	/* Clear interrupt status/mask registers in case
+	   anything was set in it. */
+	w1_imask(dev, 0);
+	w1_writel(dev, 0xFFFFFFFF, OWR_INTR_STATUS);
+	clk_disable(dev->clk);
+	return 0;
+}
+
+/* Interrupt handler for OWR communication. */
+static irqreturn_t tegra_w1_irq(int irq, void *cookie)
+{
+	unsigned long irq_flags;
+	unsigned long status;
+	struct tegra_device *dev = cookie;
+
+	status = w1_readl(dev, OWR_INTR_STATUS);
+	if (unlikely(!status)) {
+
+		/* Not for me if no status bits are set. */
+		return IRQ_NONE;
+	}
+
+	spin_lock_irqsave(&dev->spinlock, irq_flags);
+
+	if (likely(dev->transfer_completion)) {
+		dev->intr_status = status;
+		w1_writel(dev, status, OWR_INTR_STATUS);
+		complete(dev->transfer_completion);
+	} else {
+		W1_ERR("spurious interrupt, status = 0x%lx\n", status);
+	}
+
+	spin_unlock_irqrestore(&dev->spinlock, irq_flags);
+	return IRQ_HANDLED;
+}
+
+/* Perform a write-0 cycle if bit == 0, otherwise
+   perform a read cycle. */
+static u8 tegra_w1_touch_bit(void *data, u8 bit)
+{
+	int rc;
+	u8 return_bit;
+	unsigned long control;
+	DECLARE_COMPLETION_ONSTACK(touch_done);
+	struct tegra_device *dev = (struct tegra_device *) data;
+
+	return_bit = 0;
+	mutex_lock(&dev->mutex);
+	if (!dev->ready)
+		goto done;
+
+	clk_enable(dev->clk);
+	w1_imask(dev, OI_BIT_XFER_DONE);
+	dev->transfer_completion = &touch_done;
+	control =
+		((dev->timings->rdsclk & OC_RD_SCLK_MASK) << OC_RD_SCLK_SHIFT) |
+		((dev->timings->psclk & OC_P_SCLK_MASK) << OC_P_SCLK_SHIFT) |
+		OC_BIT_XMODE;
+
+	/* Read bit (well, writes a 1 to the bus as well). */
+	if (bit) {
+		w1_writel(dev, control | OC_RD_BIT, OWR_CONTROL);
+		rc = w1_wait(dev, OI_BIT_XFER_DONE);
+
+		if (rc) {
+			W1_ERR("write-1/read failed\n");
+			goto done;
+		}
+
+		return_bit =
+		    (w1_readl(dev, OWR_STATUS) >> OS_READ_BIT_SHIFT) & 1;
+
+	}
+
+	/* Write 0. */
+	else {
+		w1_writel(dev, control | OC_WR0_BIT, OWR_CONTROL);
+		rc = w1_wait(dev, OI_BIT_XFER_DONE);
+		if (rc) {
+			W1_ERR("write-0 failed\n");
+			goto done;
+		}
+	}
+
+done:
+
+	w1_imask(dev, 0);
+	dev->transfer_completion = NULL;
+	clk_disable(dev->clk);
+	mutex_unlock(&dev->mutex);
+	return return_bit;
+}
+
+/* Performs a bus reset cycle, and returns 0 if slaves present. */
+static u8 tegra_w1_reset_bus(void *data)
+{
+	int rc;
+	int presence;
+	unsigned long value;
+	DECLARE_COMPLETION_ONSTACK(reset_done);
+	struct tegra_device *dev = (struct tegra_device *) data;
+
+	presence = 1;
+	mutex_lock(&dev->mutex);
+	if (!dev->ready)
+		goto done;
+
+	clk_enable(dev->clk);
+	w1_imask(dev, OI_PRESENCE_DONE);
+	dev->transfer_completion = &reset_done;
+	value =
+	    ((dev->timings->rdsclk & OC_RD_SCLK_MASK) << OC_RD_SCLK_SHIFT) |
+	    ((dev->timings->psclk & OC_P_SCLK_MASK) << OC_P_SCLK_SHIFT) |
+	    OC_BIT_XMODE | OC_GO;
+	w1_writel(dev, value, OWR_CONTROL);
+
+	rc = w1_wait(dev, OI_PRESENCE_DONE);
+	if (rc)
+		goto done;
+
+	presence = 0;
+done:
+
+	if (debug_print & DEBUG_PRESENCE) {
+		if (presence)
+			W1_ERR("no slaves present\n");
+		else
+			W1_ERR("slaves present\n");
+	}
+
+	w1_imask(dev, 0);
+	dev->transfer_completion = NULL;
+	clk_disable(dev->clk);
+	mutex_unlock(&dev->mutex);
+	return presence;
+}
+
+static int tegra_w1_probe(struct platform_device *pdev)
+{
+	int rc;
+	int irq;
+	struct resource *res;
+	struct tegra_device *dev;
+	struct tegra_w1_platform_data *plat = pdev->dev.platform_data;
+
+	printk(KERN_INFO "Driver for Tegra SoC 1-wire controller\n");
+
+	if (plat == NULL || plat->timings == NULL)
+		return -ENXIO;
+
+	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (res == NULL)
+		return -ENODEV;
+
+	irq = res->start;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res == NULL)
+		return -ENODEV;
+
+	dev = kzalloc(sizeof(struct tegra_device), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, dev);
+	dev->clk = clk_get(&pdev->dev, plat->clk_id);
+	if (IS_ERR(dev->clk)) {
+		rc = PTR_ERR(dev->clk);
+		goto cleanup_alloc;
+	}
+
+	/* OWR requires 1MHz clock. */
+	rc = clk_set_rate(dev->clk, OWR_CLOCK);
+	if (rc)
+		goto cleanup_clock;
+
+	if (!request_mem_region
+	    (res->start, res->end - res->start + 1, dev_name(&pdev->dev))) {
+		rc = -EBUSY;
+		goto cleanup_clock;
+	}
+
+	dev->ioaddr = ioremap(res->start, res->end - res->start + 1);
+	if (!dev->ioaddr) {
+		rc = -ENOMEM;
+		goto cleanup_reqmem;
+	}
+
+	dev->timings = plat->timings;
+	dev->bus_master.data = dev;
+	dev->bus_master.touch_bit = tegra_w1_touch_bit;
+	dev->bus_master.reset_bus = tegra_w1_reset_bus;
+
+	spin_lock_init(&dev->spinlock);
+	mutex_init(&dev->mutex);
+
+	/* Program device into known state. */
+	w1_setup(dev);
+
+	rc = request_irq(irq, tegra_w1_irq, IRQF_SHARED, DRIVER_NAME, dev);
+	if (rc)
+		goto cleanup_ioremap;
+
+	rc = w1_add_master_device(&dev->bus_master);
+	if (rc)
+		goto cleanup_irq;
+
+	dev->ready = true;
+	return 0;
+
+cleanup_irq:
+	free_irq(irq, dev);
+cleanup_ioremap:
+	iounmap(dev->ioaddr);
+cleanup_reqmem:
+	release_mem_region(res->start,
+			   res->end - res->start + 1);
+cleanup_clock:
+	clk_put(dev->clk);
+cleanup_alloc:
+	platform_set_drvdata(pdev, NULL);
+	kfree(dev);
+	return rc;
+}
+
+static int tegra_w1_remove(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct tegra_device *dev = platform_get_drvdata(pdev);
+
+	mutex_lock(&dev->mutex);
+	dev->ready = false;
+	mutex_unlock(&dev->mutex);
+
+	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	free_irq(res->start, dev);
+	iounmap(dev->ioaddr);
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(res->start, res->end - res->start + 1);
+	clk_put(dev->clk);
+	platform_set_drvdata(pdev, NULL);
+	kfree(dev);
+	return 0;
+}
+
+static int tegra_w1_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	return 0;
+}
+
+static int tegra_w1_resume(struct platform_device *pdev)
+{
+	struct tegra_device *dev = platform_get_drvdata(pdev);
+
+	/* TODO: Is this necessary? I would assume yes. */
+	w1_setup(dev);
+	return 0;
+}
+
+static struct platform_driver tegra_w1_driver = {
+	.probe = tegra_w1_probe,
+	.remove = tegra_w1_remove,
+	.suspend = tegra_w1_suspend,
+	.resume = tegra_w1_resume,
+	.driver = {
+		   .name = DRIVER_NAME,
+		   .owner = THIS_MODULE,
+	},
+};
+
+static int __init tegra_w1_init(void)
+{
+	return platform_driver_register(&tegra_w1_driver);
+}
+
+static void __exit tegra_w1_exit(void)
+{
+	platform_driver_unregister(&tegra_w1_driver);
+}
+
+module_init(tegra_w1_init);
+module_exit(tegra_w1_exit);
+
+MODULE_DESCRIPTION("Tegra W1 master driver");
+MODULE_AUTHOR("Andrei Warkentin <andreiw@motorola.com>");
+MODULE_LICENSE("GPL");