[PATCH v8 2/3] i2c: iproc: Add Broadcom iProc I2C Driver

[Ray Jui <rjui@broadcom.com>]

Add initial support to the Broadcom iProc I2C controller found in the
iProc family of SoCs.

The iProc I2C controller has separate internal TX and RX FIFOs, each has
a size of 64 bytes. The iProc I2C controller supports two bus speeds
including standard mode (100kHz) and fast mode (400kHz)

Signed-off-by: Ray Jui <rjui@broadcom.com>
Reviewed-by: Scott Branden <sbranden@broadcom.com>
Reviewed-by: Kevin Cernekee <cernekee@chromium.org>
---
 drivers/i2c/busses/Kconfig         |   10 +
 drivers/i2c/busses/Makefile        |    1 +
 drivers/i2c/busses/i2c-bcm-iproc.c |  494 ++++++++++++++++++++++++++++++++++++
 3 files changed, 505 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-bcm-iproc.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index ab838d9..3d08731 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -372,6 +372,16 @@ config I2C_BCM2835
 	  This support is also available as a module.  If so, the module
 	  will be called i2c-bcm2835.
 
+config I2C_BCM_IPROC
+	tristate "Broadcom iProc I2C controller"
+	depends on ARCH_BCM_IPROC || COMPILE_TEST
+	default ARCH_BCM_IPROC
+	help
+	  If you say yes to this option, support will be included for the
+	  Broadcom iProc I2C controller.
+
+	  If you don't know what to do here, say N.
+
 config I2C_BCM_KONA
 	tristate "BCM Kona I2C adapter"
 	depends on ARCH_BCM_MOBILE
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 56388f6..d93b509 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -33,6 +33,7 @@ obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o
 obj-$(CONFIG_I2C_AU1550)	+= i2c-au1550.o
 obj-$(CONFIG_I2C_AXXIA)		+= i2c-axxia.o
 obj-$(CONFIG_I2C_BCM2835)	+= i2c-bcm2835.o
+obj-$(CONFIG_I2C_BCM_IPROC)	+= i2c-bcm-iproc.o
 obj-$(CONFIG_I2C_BLACKFIN_TWI)	+= i2c-bfin-twi.o
 obj-$(CONFIG_I2C_CADENCE)	+= i2c-cadence.o
 obj-$(CONFIG_I2C_CBUS_GPIO)	+= i2c-cbus-gpio.o
diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
new file mode 100644
index 0000000..5d0a03f
--- /dev/null
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -0,0 +1,494 @@
+/*
+ * Copyright (C) 2014 Broadcom Corporation
+ *
+ * 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 version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+
+#define CFG_OFFSET                   0x00
+#define CFG_RESET_SHIFT              31
+#define CFG_EN_SHIFT                 30
+#define CFG_M_RETRY_CNT_SHIFT        16
+#define CFG_M_RETRY_CNT_MASK         0x0f
+
+#define TIM_CFG_OFFSET               0x04
+#define TIM_CFG_MODE_400_SHIFT       31
+
+#define M_FIFO_CTRL_OFFSET           0x0c
+#define M_FIFO_RX_FLUSH_SHIFT        31
+#define M_FIFO_TX_FLUSH_SHIFT        30
+#define M_FIFO_RX_CNT_SHIFT          16
+#define M_FIFO_RX_CNT_MASK           0x7f
+#define M_FIFO_RX_THLD_SHIFT         8
+#define M_FIFO_RX_THLD_MASK          0x3f
+
+#define M_CMD_OFFSET                 0x30
+#define M_CMD_START_BUSY_SHIFT       31
+#define M_CMD_STATUS_SHIFT           25
+#define M_CMD_STATUS_MASK            0x07
+#define M_CMD_STATUS_SUCCESS         0x0
+#define M_CMD_STATUS_LOST_ARB        0x1
+#define M_CMD_STATUS_NACK_ADDR       0x2
+#define M_CMD_STATUS_NACK_DATA       0x3
+#define M_CMD_STATUS_TIMEOUT         0x4
+#define M_CMD_PROTOCOL_SHIFT         9
+#define M_CMD_PROTOCOL_MASK          0xf
+#define M_CMD_PROTOCOL_BLK_WR        0x7
+#define M_CMD_PROTOCOL_BLK_RD        0x8
+#define M_CMD_PEC_SHIFT              8
+#define M_CMD_RD_CNT_SHIFT           0
+#define M_CMD_RD_CNT_MASK            0xff
+
+#define IE_OFFSET                    0x38
+#define IE_M_RX_FIFO_FULL_SHIFT      31
+#define IE_M_RX_THLD_SHIFT           30
+#define IE_M_START_BUSY_SHIFT        28
+
+#define IS_OFFSET                    0x3c
+#define IS_M_RX_FIFO_FULL_SHIFT      31
+#define IS_M_RX_THLD_SHIFT           30
+#define IS_M_START_BUSY_SHIFT        28
+
+#define M_TX_OFFSET                  0x40
+#define M_TX_WR_STATUS_SHIFT         31
+#define M_TX_DATA_SHIFT              0
+#define M_TX_DATA_MASK               0xff
+
+#define M_RX_OFFSET                  0x44
+#define M_RX_STATUS_SHIFT            30
+#define M_RX_STATUS_MASK             0x03
+#define M_RX_PEC_ERR_SHIFT           29
+#define M_RX_DATA_SHIFT              0
+#define M_RX_DATA_MASK               0xff
+
+#define I2C_TIMEOUT_MESC             100
+#define M_TX_RX_FIFO_SIZE            64
+
+enum bus_speed_index {
+	I2C_SPD_100K = 0,
+	I2C_SPD_400K,
+};
+
+struct bcm_iproc_i2c_dev {
+	struct device *device;
+	int irq;
+
+	void __iomem *base;
+
+	struct i2c_adapter adapter;
+
+	struct completion done;
+	int xfer_is_done;
+};
+
+/*
+ * Can be expanded in the future if more interrupt status bits are utilized
+ */
+#define ISR_MASK (1 << IS_M_START_BUSY_SHIFT)
+
+static irqreturn_t bcm_iproc_i2c_isr(int irq, void *data)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = data;
+	u32 status = readl(iproc_i2c->base + IS_OFFSET);
+
+	status &= ISR_MASK;
+
+	if (!status)
+		return IRQ_NONE;
+
+	writel(status, iproc_i2c->base + IS_OFFSET);
+	iproc_i2c->xfer_is_done = 1;
+	complete_all(&iproc_i2c->done);
+
+	return IRQ_HANDLED;
+}
+
+static bool bcm_iproc_i2c_bus_busy(struct bcm_iproc_i2c_dev *iproc_i2c)
+{
+	if (readl(iproc_i2c->base + M_CMD_OFFSET) &
+	    (1 << M_CMD_START_BUSY_SHIFT))
+		return true;
+	else
+		return false;
+}
+
+static int bcm_iproc_i2c_format_addr(struct bcm_iproc_i2c_dev *iproc_i2c,
+				     struct i2c_msg *msg, u8 *addr)
+{
+	*addr = msg->addr << 1;
+
+	if (msg->flags & I2C_M_RD)
+		*addr |= 1;
+
+	return 0;
+}
+
+static int bcm_iproc_i2c_check_status(struct bcm_iproc_i2c_dev *iproc_i2c,
+				      struct i2c_msg *msg)
+{
+	u32 val;
+
+	val = readl(iproc_i2c->base + M_CMD_OFFSET);
+	val = (val >> M_CMD_STATUS_SHIFT) & M_CMD_STATUS_MASK;
+
+	switch (val) {
+	case M_CMD_STATUS_SUCCESS:
+		return 0;
+
+	case M_CMD_STATUS_LOST_ARB:
+		dev_dbg(iproc_i2c->device, "lost bus arbitration\n");
+		return -EAGAIN;
+
+	case M_CMD_STATUS_NACK_ADDR:
+		dev_dbg(iproc_i2c->device, "NAK addr:0x%02x\n", msg->addr);
+		return -ENXIO;
+
+	case M_CMD_STATUS_NACK_DATA:
+		dev_dbg(iproc_i2c->device, "NAK data\n");
+		return -ENXIO;
+
+	case M_CMD_STATUS_TIMEOUT:
+		dev_dbg(iproc_i2c->device, "bus timeout\n");
+		return -ETIMEDOUT;
+
+	default:
+		dev_dbg(iproc_i2c->device, "unknown error code=%d\n", val);
+		return -EIO;
+	}
+}
+
+static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
+					 struct i2c_msg *msg)
+{
+	int ret, i;
+	u8 addr;
+	u32 val;
+	unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT_MESC);
+
+	/* need to reserve one byte in the FIFO for the slave address */
+	if (msg->len > M_TX_RX_FIFO_SIZE - 1) {
+		dev_err(iproc_i2c->device,
+			"only support data length up to %u bytes\n",
+			M_TX_RX_FIFO_SIZE - 1);
+		return -EINVAL;
+	}
+
+	if (bcm_iproc_i2c_bus_busy(iproc_i2c)) {
+		dev_warn(iproc_i2c->device, "bus is busy\n");
+		return -EBUSY;
+	}
+
+	ret = bcm_iproc_i2c_format_addr(iproc_i2c, msg, &addr);
+	if (ret)
+		return ret;
+
+	/* load slave address into the TX FIFO */
+	writel(addr, iproc_i2c->base + M_TX_OFFSET);
+
+	/* for a write transaction, load data into the TX FIFO */
+	if (!(msg->flags & I2C_M_RD)) {
+		for (i = 0; i < msg->len; i++) {
+			val = msg->buf[i];
+
+			/* mark the last byte */
+			if (i == msg->len - 1)
+				val |= 1 << M_TX_WR_STATUS_SHIFT;
+
+			writel(val, iproc_i2c->base + M_TX_OFFSET);
+		}
+	}
+
+	/* mark as incomplete before starting the transaction */
+	reinit_completion(&iproc_i2c->done);
+	iproc_i2c->xfer_is_done = 0;
+
+	/*
+	 * Enable the "start busy" interrupt, which will be triggered after the
+	 * transaction is done, i.e., the internal start_busy bit, transitions
+	 * from 1 to 0.
+	 */
+	writel(1 << IE_M_START_BUSY_SHIFT, iproc_i2c->base + IE_OFFSET);
+
+	/*
+	 * Now we can activate the transfer. For a read operation, specify the
+	 * number of bytes to read
+	 */
+	val = 1 << M_CMD_START_BUSY_SHIFT;
+	if (msg->flags & I2C_M_RD) {
+		val |= (M_CMD_PROTOCOL_BLK_RD << M_CMD_PROTOCOL_SHIFT) |
+		       (msg->len << M_CMD_RD_CNT_SHIFT);
+	} else {
+		val |= (M_CMD_PROTOCOL_BLK_WR << M_CMD_PROTOCOL_SHIFT);
+	}
+	writel(val, iproc_i2c->base + M_CMD_OFFSET);
+
+	time_left = wait_for_completion_timeout(&iproc_i2c->done, time_left);
+
+	/* disable all interrupts */
+	writel(0, iproc_i2c->base + IE_OFFSET);
+	/* read it back to flush the write */
+	readl(iproc_i2c->base + IE_OFFSET);
+
+	/* make sure the interrupt handler isn't running */
+	synchronize_irq(iproc_i2c->irq);
+
+	if (!time_left && !iproc_i2c->xfer_is_done) {
+		dev_err(iproc_i2c->device, "transaction timed out\n");
+
+		/* flush FIFOs */
+		val = (1 << M_FIFO_RX_FLUSH_SHIFT) |
+		      (1 << M_FIFO_TX_FLUSH_SHIFT);
+		writel(val, iproc_i2c->base + M_FIFO_CTRL_OFFSET);
+		return -ETIMEDOUT;
+	}
+
+	ret = bcm_iproc_i2c_check_status(iproc_i2c, msg);
+	if (ret) {
+		/* flush both TX/RX FIFOs */
+		val = (1 << M_FIFO_RX_FLUSH_SHIFT) |
+		      (1 << M_FIFO_TX_FLUSH_SHIFT);
+		writel(val, iproc_i2c->base + M_FIFO_CTRL_OFFSET);
+		return ret;
+	}
+
+	/*
+	 * For a read operation, we now need to load the data from FIFO
+	 * into the memory buffer
+	 */
+	if (msg->flags & I2C_M_RD) {
+		for (i = 0; i < msg->len; i++) {
+			msg->buf[i] = (readl(iproc_i2c->base + M_RX_OFFSET) >>
+				      M_RX_DATA_SHIFT) & M_RX_DATA_MASK;
+		}
+	}
+
+	dev_dbg(iproc_i2c->device, "xfer %c, addr=0x%02x, len=%d\n",
+		(msg->flags & I2C_M_RD) ? 'R' : 'W', msg->addr,
+		msg->len);
+	dev_dbg(iproc_i2c->device, "*** data: %*ph\n", msg->len, msg->buf);
+
+	return 0;
+}
+
+static int bcm_iproc_i2c_xfer(struct i2c_adapter *adapter,
+			      struct i2c_msg msgs[], int num)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adapter);
+	int ret, i;
+
+	/* go through all messages */
+	for (i = 0; i < num; i++) {
+		ret = bcm_iproc_i2c_xfer_single_msg(iproc_i2c, &msgs[i]);
+		if (ret) {
+			dev_dbg(iproc_i2c->device, "xfer failed\n");
+			return ret;
+		}
+	}
+
+	return num;
+}
+
+static uint32_t bcm_iproc_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm bcm_iproc_algo = {
+	.master_xfer = bcm_iproc_i2c_xfer,
+	.functionality = bcm_iproc_i2c_functionality,
+};
+
+static int bcm_iproc_i2c_cfg_speed(struct bcm_iproc_i2c_dev *iproc_i2c)
+{
+	unsigned int bus_speed, speed_bit;
+	u32 val;
+	int ret = of_property_read_u32(iproc_i2c->device->of_node,
+				       "clock-frequency", &bus_speed);
+	if (ret < 0) {
+		dev_info(iproc_i2c->device,
+			"unable to interpret clock-frequency DT property\n");
+		bus_speed = 100000;
+	}
+
+	if (bus_speed < 100000) {
+		dev_err(iproc_i2c->device, "%d Hz bus speed not supported\n",
+			bus_speed);
+		dev_err(iproc_i2c->device,
+			"valid speeds are 100khz and 400khz\n");
+		return -EINVAL;
+	} else if (bus_speed < 400000) {
+		bus_speed = 100000;
+		speed_bit = 0;
+	} else {
+		bus_speed = 400000;
+		speed_bit = 1;
+	}
+
+	val = readl(iproc_i2c->base + TIM_CFG_OFFSET);
+	val &= ~(1 << TIM_CFG_MODE_400_SHIFT);
+	val |= speed_bit << TIM_CFG_MODE_400_SHIFT;
+	writel(val, iproc_i2c->base + TIM_CFG_OFFSET);
+
+	dev_info(iproc_i2c->device, "bus set to %u Hz\n", bus_speed);
+
+	return 0;
+}
+
+static int bcm_iproc_i2c_init(struct bcm_iproc_i2c_dev *iproc_i2c)
+{
+	u32 val;
+
+	/* put controller in reset */
+	val = readl(iproc_i2c->base + CFG_OFFSET);
+	val |= 1 << CFG_RESET_SHIFT;
+	val &= ~(1 << CFG_EN_SHIFT);
+	writel(val, iproc_i2c->base + CFG_OFFSET);
+
+	/* wait 100 usec per spec */
+	udelay(100);
+
+	/* bring controller out of reset */
+	val &= ~(1 << CFG_RESET_SHIFT);
+	writel(val, iproc_i2c->base + CFG_OFFSET);
+
+	/* flush TX/RX FIFOs and set RX FIFO threshold to zero */
+	val = (1 << M_FIFO_RX_FLUSH_SHIFT) | (1 << M_FIFO_TX_FLUSH_SHIFT);
+	writel(val, iproc_i2c->base + M_FIFO_CTRL_OFFSET);
+
+	/* disable all interrupts */
+	writel(0, iproc_i2c->base + IE_OFFSET);
+
+	/* clear all pending interrupts */
+	writel(0xffffffff, iproc_i2c->base + IS_OFFSET);
+
+	return 0;
+}
+
+static void bcm_iproc_i2c_enable(struct bcm_iproc_i2c_dev *iproc_i2c)
+{
+	u32 val;
+
+	val = readl(iproc_i2c->base + CFG_OFFSET);
+	val |= 1 << CFG_EN_SHIFT;
+	writel(val, iproc_i2c->base + CFG_OFFSET);
+}
+
+static void bcm_iproc_i2c_disable(struct bcm_iproc_i2c_dev *iproc_i2c)
+{
+	u32 val;
+
+	val = readl(iproc_i2c->base + CFG_OFFSET);
+	val &= ~(1 << CFG_EN_SHIFT);
+	writel(val, iproc_i2c->base + CFG_OFFSET);
+}
+
+static int bcm_iproc_i2c_probe(struct platform_device *pdev)
+{
+	int irq, ret = 0;
+	struct bcm_iproc_i2c_dev *iproc_i2c;
+	struct i2c_adapter *adap;
+	struct resource *res;
+
+	iproc_i2c = devm_kzalloc(&pdev->dev, sizeof(*iproc_i2c),
+				 GFP_KERNEL);
+	if (!iproc_i2c)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, iproc_i2c);
+	iproc_i2c->device = &pdev->dev;
+	init_completion(&iproc_i2c->done);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	iproc_i2c->base = devm_ioremap_resource(iproc_i2c->device, res);
+	if (IS_ERR(iproc_i2c->base))
+		return PTR_ERR(iproc_i2c->base);
+
+	ret = bcm_iproc_i2c_init(iproc_i2c);
+	if (ret)
+		return ret;
+
+	ret = bcm_iproc_i2c_cfg_speed(iproc_i2c);
+	if (ret)
+		return ret;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq <= 0) {
+		dev_err(iproc_i2c->device, "no irq resource\n");
+		return irq;
+	}
+	iproc_i2c->irq = irq;
+
+	ret = devm_request_irq(iproc_i2c->device, irq, bcm_iproc_i2c_isr, 0,
+			       pdev->name, iproc_i2c);
+	if (ret < 0) {
+		dev_err(iproc_i2c->device, "unable to request irq %i\n", irq);
+		return ret;
+	}
+
+	bcm_iproc_i2c_enable(iproc_i2c);
+
+	adap = &iproc_i2c->adapter;
+	i2c_set_adapdata(adap, iproc_i2c);
+	strlcpy(adap->name, "Broadcom iProc I2C adapter", sizeof(adap->name));
+	adap->algo = &bcm_iproc_algo;
+	adap->dev.parent = &pdev->dev;
+	adap->dev.of_node = pdev->dev.of_node;
+
+	ret = i2c_add_adapter(adap);
+	if (ret) {
+		dev_err(iproc_i2c->device, "failed to add adapter\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int bcm_iproc_i2c_remove(struct platform_device *pdev)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = platform_get_drvdata(pdev);
+
+	/* make sure there's no pending interrupt when we remove the adapter */
+	writel(0, iproc_i2c->base + IE_OFFSET);
+	readl(iproc_i2c->base + IE_OFFSET);
+	synchronize_irq(iproc_i2c->irq);
+
+	i2c_del_adapter(&iproc_i2c->adapter);
+	bcm_iproc_i2c_disable(iproc_i2c);
+
+	return 0;
+}
+
+static const struct of_device_id bcm_iproc_i2c_of_match[] = {
+	{ .compatible = "brcm,iproc-i2c" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, bcm_iproc_i2c_of_match);
+
+static struct platform_driver bcm_iproc_i2c_driver = {
+	.driver = {
+		.name = "bcm-iproc-i2c",
+		.of_match_table = bcm_iproc_i2c_of_match,
+	},
+	.probe = bcm_iproc_i2c_probe,
+	.remove = bcm_iproc_i2c_remove,
+};
+module_platform_driver(bcm_iproc_i2c_driver);
+
+MODULE_AUTHOR("Ray Jui <rjui@broadcom.com>");
+MODULE_DESCRIPTION("Broadcom iProc I2C Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5