Date:	Thu, 29 Jan 2015 10:20:21 +0300
From:	Andrey Danin <danindrey@...l.ru>
To:	ac100@...ts.launchpad.net, linux-tegra@...r.kernel.org,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Cc:	Andrey Danin <danindrey@...l.ru>,
	Julian Andres Klode <jak@...-linux.org>,
	Marc Dietrich <marvin24@....de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH 2/3] staging/nvec: reimplement on top of tegra i2c driver

Remove i2c controller related code and use tegra i2c driver in slave mode.

Signed-off-by: Andrey Danin <danindrey@...l.ru>
---
 drivers/staging/nvec/nvec.c | 379 ++++++++++++++------------------------------
 drivers/staging/nvec/nvec.h |  17 +-
 2 files changed, 122 insertions(+), 274 deletions(-)

diff --git a/drivers/staging/nvec/nvec.c b/drivers/staging/nvec/nvec.c
index 120b70d..d645c58 100644
--- a/drivers/staging/nvec/nvec.c
+++ b/drivers/staging/nvec/nvec.c
@@ -25,8 +25,8 @@
 #include <linux/err.h>
 #include <linux/gpio.h>
 #include <linux/interrupt.h>
+#include <linux/i2c.h>
 #include <linux/io.h>
-#include <linux/irq.h>
 #include <linux/of.h>
 #include <linux/of_gpio.h>
 #include <linux/list.h>
@@ -39,25 +39,12 @@
 
 #include "nvec.h"
 
-#define I2C_CNFG			0x00
-#define I2C_CNFG_PACKET_MODE_EN		(1<<10)
-#define I2C_CNFG_NEW_MASTER_SFM		(1<<11)
-#define I2C_CNFG_DEBOUNCE_CNT_SHIFT	12
-
-#define I2C_SL_CNFG		0x20
-#define I2C_SL_NEWSL		(1<<2)
-#define I2C_SL_NACK		(1<<1)
-#define I2C_SL_RESP		(1<<0)
-#define I2C_SL_IRQ		(1<<3)
-#define END_TRANS		(1<<4)
-#define RCVD			(1<<2)
-#define RNW			(1<<1)
-
-#define I2C_SL_RCVD		0x24
-#define I2C_SL_STATUS		0x28
-#define I2C_SL_ADDR1		0x2c
-#define I2C_SL_ADDR2		0x30
-#define I2C_SL_DELAY_COUNT	0x3c
+
+#define I2C_SL_ST_END_TRANS			(1<<4)
+#define I2C_SL_ST_IRQ				(1<<3)
+#define I2C_SL_ST_RCVD				(1<<2)
+#define I2C_SL_ST_RNW				(1<<1)
+
 
 /**
  * enum nvec_msg_category - Message categories for nvec_msg_alloc()
@@ -327,6 +314,7 @@ struct nvec_msg *nvec_write_sync(struct nvec_chip *nvec,
 
 	mutex_unlock(&nvec->sync_write_mutex);
 
+
 	return msg;
 }
 EXPORT_SYMBOL(nvec_write_sync);
@@ -475,11 +463,13 @@ static void nvec_tx_completed(struct nvec_chip *nvec)
 {
 	/* We got an END_TRANS, let's skip this, maybe there's an event */
 	if (nvec->tx->pos != nvec->tx->size) {
-		dev_err(nvec->dev, "premature END_TRANS, resending\n");
+		dev_err(nvec->dev, "premature END_TRANS, resending: pos:%u, size:%u\n",
+				nvec->tx->pos, nvec->tx->size);
 		nvec->tx->pos = 0;
 		nvec_gpio_set_value(nvec, 0);
 	} else {
-		nvec->state = 0;
+		nvec->state = ST_NONE;
+		nvec->tx->pos = 0;
 	}
 }
 
@@ -497,7 +487,7 @@ static void nvec_rx_completed(struct nvec_chip *nvec)
 			   (uint) nvec->rx->pos);
 
 		nvec_msg_free(nvec, nvec->rx);
-		nvec->state = 0;
+		nvec->state = ST_NONE;
 
 		/* Battery quirk - Often incomplete, and likes to crash */
 		if (nvec->rx->data[0] == NVEC_BAT)
@@ -514,7 +504,7 @@ static void nvec_rx_completed(struct nvec_chip *nvec)
 
 	spin_unlock(&nvec->rx_lock);
 
-	nvec->state = 0;
+	nvec->state = ST_NONE;
 
 	if (!nvec_msg_is_event(nvec->rx))
 		complete(&nvec->ec_transfer);
@@ -523,21 +513,6 @@ static void nvec_rx_completed(struct nvec_chip *nvec)
 }
 
 /**
- * nvec_invalid_flags - Send an error message about invalid flags and jump
- * @nvec: The nvec device
- * @status: The status flags
- * @reset: Whether we shall jump to state 0.
- */
-static void nvec_invalid_flags(struct nvec_chip *nvec, unsigned int status,
-			       bool reset)
-{
-	dev_err(nvec->dev, "unexpected status flags 0x%02x during state %i\n",
-		status, nvec->state);
-	if (reset)
-		nvec->state = 0;
-}
-
-/**
  * nvec_tx_set - Set the message to transfer (nvec->tx)
  * @nvec: A &struct nvec_chip
  *
@@ -566,150 +541,85 @@ static void nvec_tx_set(struct nvec_chip *nvec)
 		(uint)nvec->tx->size, nvec->tx->data[1]);
 }
 
+
 /**
- * nvec_interrupt - Interrupt handler
- * @irq: The IRQ
- * @dev: The nvec device
+ * nvec_slave_cb - I2C slave callback
  *
- * Interrupt handler that fills our RX buffers and empties our TX
- * buffers. This uses a finite state machine with ridiculous amounts
- * of error checking, in order to be fairly reliable.
+ * This callback fills our RX buffers and empties our TX
+ * buffers. This uses a finite state machine.
  */
-static irqreturn_t nvec_interrupt(int irq, void *dev)
+static int nvec_slave_cb(struct i2c_client *client,
+		enum i2c_slave_event event, u8 *val)
 {
-	unsigned long status;
-	unsigned int received = 0;
-	unsigned char to_send = 0xff;
-	const unsigned long irq_mask = I2C_SL_IRQ | END_TRANS | RCVD | RNW;
-	struct nvec_chip *nvec = dev;
-	unsigned int state = nvec->state;
-
-	status = readl(nvec->base + I2C_SL_STATUS);
-
-	/* Filter out some errors */
-	if ((status & irq_mask) == 0 && (status & ~irq_mask) != 0) {
-		dev_err(nvec->dev, "unexpected irq mask %lx\n", status);
-		return IRQ_HANDLED;
-	}
-	if ((status & I2C_SL_IRQ) == 0) {
-		dev_err(nvec->dev, "Spurious IRQ\n");
-		return IRQ_HANDLED;
-	}
-
-	/* The EC did not request a read, so it send us something, read it */
-	if ((status & RNW) == 0) {
-		received = readl(nvec->base + I2C_SL_RCVD);
-		if (status & RCVD)
-			writel(0, nvec->base + I2C_SL_RCVD);
-	}
+	struct nvec_chip *nvec = i2c_get_clientdata(client);
 
-	if (status == (I2C_SL_IRQ | RCVD))
-		nvec->state = 0;
-
-	switch (nvec->state) {
-	case 0:		/* Verify that its a transfer start, the rest later */
-		if (status != (I2C_SL_IRQ | RCVD))
-			nvec_invalid_flags(nvec, status, false);
-		break;
-	case 1:		/* command byte */
-		if (status != I2C_SL_IRQ) {
-			nvec_invalid_flags(nvec, status, true);
-		} else {
+	switch (event) {
+	case I2C_SLAVE_REQ_WRITE_END:
+		if (nvec->state == ST_NONE) {
 			nvec->rx = nvec_msg_alloc(nvec, NVEC_MSG_RX);
 			/* Should not happen in a normal world */
 			if (unlikely(nvec->rx == NULL)) {
-				nvec->state = 0;
-				break;
+				nvec->state = ST_NONE;
+				return -1;
 			}
-			nvec->rx->data[0] = received;
-			nvec->rx->pos = 1;
-			nvec->state = 2;
+			nvec->rx->pos = 0;
+
+			if (client->addr != ((*val) >> 1)) {
+				dev_err(&client->dev,
+				"received address 0x%02x, expected 0x%02x\n",
+				((*val) >> 1), client->addr);
+			}
+			nvec->state = ST_TRANS_START;
+			nvec->rx->pos = 0;
+			break;
 		}
+
+		nvec->rx->data[nvec->rx->pos++] = *val;
+		nvec->state = ST_RX;
 		break;
-	case 2:		/* first byte after command */
-		if (status == (I2C_SL_IRQ | RNW | RCVD)) {
-			udelay(33);
-			if (nvec->rx->data[0] != 0x01) {
-				dev_err(nvec->dev,
-					"Read without prior read command\n");
-				nvec->state = 0;
-				break;
-			}
+
+	case I2C_SLAVE_REQ_READ_START:
+		if (nvec->state == ST_NONE) {
+			dev_err(&client->dev,
+			"unexpected read without transaction start, state %d\n",
+			nvec->state);
+			return -1;
+		}
+
+		if (nvec->state == ST_RX) {
 			nvec_msg_free(nvec, nvec->rx);
-			nvec->state = 3;
 			nvec_tx_set(nvec);
-			BUG_ON(nvec->tx->size < 1);
-			to_send = nvec->tx->data[0];
-			nvec->tx->pos = 1;
-		} else if (status == (I2C_SL_IRQ)) {
-			BUG_ON(nvec->rx == NULL);
-			nvec->rx->data[1] = received;
-			nvec->rx->pos = 2;
-			nvec->state = 4;
-		} else {
-			nvec_invalid_flags(nvec, status, true);
 		}
-		break;
-	case 3:		/* EC does a block read, we transmit data */
-		if (status & END_TRANS) {
-			nvec_tx_completed(nvec);
-		} else if ((status & RNW) == 0 || (status & RCVD)) {
-			nvec_invalid_flags(nvec, status, true);
-		} else if (nvec->tx && nvec->tx->pos < nvec->tx->size) {
-			to_send = nvec->tx->data[nvec->tx->pos++];
-		} else {
+
+		if (!nvec->tx || nvec->tx->pos >= nvec->tx->size) {
 			dev_err(nvec->dev, "tx buffer underflow on %p (%u > %u)\n",
 				nvec->tx,
 				(uint) (nvec->tx ? nvec->tx->pos : 0),
 				(uint) (nvec->tx ? nvec->tx->size : 0));
-			nvec->state = 0;
+			nvec->state = ST_NONE;
+			break;
 		}
-		break;
-	case 4:		/* EC does some write, we read the data */
-		if ((status & (END_TRANS | RNW)) == END_TRANS)
-			nvec_rx_completed(nvec);
-		else if (status & (RNW | RCVD))
-			nvec_invalid_flags(nvec, status, true);
-		else if (nvec->rx && nvec->rx->pos < NVEC_MSG_SIZE)
-			nvec->rx->data[nvec->rx->pos++] = received;
-		else
-			dev_err(nvec->dev,
-				"RX buffer overflow on %p: Trying to write byte %u of %u\n",
-				nvec->rx, nvec->rx ? nvec->rx->pos : 0,
-				NVEC_MSG_SIZE);
-		break;
-	default:
-		nvec->state = 0;
-	}
-
-	/* If we are told that a new transfer starts, verify it */
-	if ((status & (RCVD | RNW)) == RCVD) {
-		if (received != nvec->i2c_addr)
-			dev_err(nvec->dev,
-			"received address 0x%02x, expected 0x%02x\n",
-			received, nvec->i2c_addr);
-		nvec->state = 1;
-	}
 
-	/* Send data if requested, but not on end of transmission */
-	if ((status & (RNW | END_TRANS)) == RNW)
-		writel(to_send, nvec->base + I2C_SL_RCVD);
+		nvec->state = ST_TX;
+		*val = nvec->tx->data[nvec->tx->pos];
+		break;
 
-	/* If we have send the first byte */
-	if (status == (I2C_SL_IRQ | RNW | RCVD))
+	case I2C_SLAVE_REQ_READ_END:
+		nvec->tx->pos++;
 		nvec_gpio_set_value(nvec, 1);
+		break;
 
-	dev_dbg(nvec->dev,
-		"Handled: %s 0x%02x, %s 0x%02x in state %u [%s%s%s]\n",
-		(status & RNW) == 0 ? "received" : "R=",
-		received,
-		(status & (RNW | END_TRANS)) ? "sent" : "S=",
-		to_send,
-		state,
-		status & END_TRANS ? " END_TRANS" : "",
-		status & RCVD ? " RCVD" : "",
-		status & RNW ? " RNW" : "");
+	case I2C_SLAVE_STOP:
+		if (nvec->state == ST_TX)
+			nvec_tx_completed(nvec);
+		else if (nvec->state == ST_RX)
+			nvec_rx_completed(nvec);
+		nvec->state = ST_NONE;
+		break;
 
+	default:
+		return 0;
+	}
 
 	/*
 	 * TODO: A correct fix needs to be found for this.
@@ -717,44 +627,18 @@ static irqreturn_t nvec_interrupt(int irq, void *dev)
 	 * We experience less incomplete messages with this delay than without
 	 * it, but we don't know why. Help is appreciated.
 	 */
-	udelay(100);
-
-	return IRQ_HANDLED;
-}
-
-static void tegra_init_i2c_slave(struct nvec_chip *nvec)
-{
-	u32 val;
-
-	clk_prepare_enable(nvec->i2c_clk);
-
-	reset_control_assert(nvec->rst);
-	udelay(2);
-	reset_control_deassert(nvec->rst);
-
-	val = I2C_CNFG_NEW_MASTER_SFM | I2C_CNFG_PACKET_MODE_EN |
-	    (0x2 << I2C_CNFG_DEBOUNCE_CNT_SHIFT);
-	writel(val, nvec->base + I2C_CNFG);
-
-	clk_set_rate(nvec->i2c_clk, 8 * 80000);
-
-	writel(I2C_SL_NEWSL, nvec->base + I2C_SL_CNFG);
-	writel(0x1E, nvec->base + I2C_SL_DELAY_COUNT);
-
-	writel(nvec->i2c_addr>>1, nvec->base + I2C_SL_ADDR1);
-	writel(0, nvec->base + I2C_SL_ADDR2);
-
-	enable_irq(nvec->irq);
-}
+	switch (event) {
+	case I2C_SLAVE_REQ_WRITE_END:
+	case I2C_SLAVE_REQ_READ_END:
+	case I2C_SLAVE_STOP:
+		udelay(100);
+		break;
+	default:
+		break;
+	}
 
-#ifdef CONFIG_PM_SLEEP
-static void nvec_disable_i2c_slave(struct nvec_chip *nvec)
-{
-	disable_irq(nvec->irq);
-	writel(I2C_SL_NEWSL | I2C_SL_NACK, nvec->base + I2C_SL_CNFG);
-	clk_disable_unprepare(nvec->i2c_clk);
+	return 0;
 }
-#endif
 
 static void nvec_power_off(void)
 {
@@ -767,7 +651,7 @@ static void nvec_power_off(void)
 /*
  *  Parse common device tree data
  */
-static int nvec_i2c_parse_dt_pdata(struct nvec_chip *nvec)
+static int nvec_i2c_parse_dt(struct nvec_chip *nvec)
 {
 	nvec->gpio = of_get_named_gpio(nvec->dev->of_node, "request-gpios", 0);
 
@@ -776,68 +660,39 @@ static int nvec_i2c_parse_dt_pdata(struct nvec_chip *nvec)
 		return -ENODEV;
 	}
 
-	if (of_property_read_u32(nvec->dev->of_node, "slave-addr",
-				&nvec->i2c_addr)) {
-		dev_err(nvec->dev, "no i2c address specified");
-		return -ENODEV;
-	}
-
 	return 0;
 }
 
-static int tegra_nvec_probe(struct platform_device *pdev)
+static int nvec_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
-	int err, ret;
-	struct clk *i2c_clk;
+	int ret;
 	struct nvec_chip *nvec;
 	struct nvec_msg *msg;
-	struct resource *res;
-	void __iomem *base;
-	char	get_firmware_version[] = { NVEC_CNTL, GET_FIRMWARE_VERSION },
+	char    get_firmware_version[] = { NVEC_CNTL, GET_FIRMWARE_VERSION },
 		unmute_speakers[] = { NVEC_OEM0, 0x10, 0x59, 0x95 },
 		enable_event[7] = { NVEC_SYS, CNF_EVENT_REPORTING, true };
 
-	if (!pdev->dev.of_node) {
-		dev_err(&pdev->dev, "must be instantiated using device tree\n");
+
+	if (!client->dev.of_node) {
+		dev_err(&client->dev, "must be instantiated using device tree\n");
 		return -ENODEV;
 	}
 
-	nvec = devm_kzalloc(&pdev->dev, sizeof(struct nvec_chip), GFP_KERNEL);
+	nvec = devm_kzalloc(&client->dev, sizeof(struct nvec_chip), GFP_KERNEL);
 	if (nvec == NULL)
 		return -ENOMEM;
 
-	platform_set_drvdata(pdev, nvec);
-	nvec->dev = &pdev->dev;
+	nvec->dev = &client->dev;
+	ret = nvec_i2c_parse_dt(nvec);
+	if (ret < 0)
+		return ret;
 
-	err = nvec_i2c_parse_dt_pdata(nvec);
-	if (err < 0)
-		return err;
+	i2c_set_clientdata(client, nvec);
 
-	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	base = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(base))
-		return PTR_ERR(base);
-
-	nvec->irq = platform_get_irq(pdev, 0);
-	if (nvec->irq < 0) {
-		dev_err(&pdev->dev, "no irq resource?\n");
-		return -ENODEV;
-	}
-
-	i2c_clk = devm_clk_get(&pdev->dev, "div-clk");
-	if (IS_ERR(i2c_clk)) {
-		dev_err(nvec->dev, "failed to get controller clock\n");
-		return -ENODEV;
-	}
-
-	nvec->rst = devm_reset_control_get(&pdev->dev, "i2c");
-	if (IS_ERR(nvec->rst)) {
-		dev_err(nvec->dev, "failed to get controller reset\n");
-		return PTR_ERR(nvec->rst);
-	}
+	ret = i2c_slave_register(client, nvec_slave_cb);
+	if (ret < 0)
+		return ret;
 
-	nvec->base = base;
-	nvec->i2c_clk = i2c_clk;
 	nvec->rx = &nvec->msg_pool[0];
 
 	ATOMIC_INIT_NOTIFIER_HEAD(&nvec->notifier_list);
@@ -852,23 +707,14 @@ static int tegra_nvec_probe(struct platform_device *pdev)
 	INIT_WORK(&nvec->rx_work, nvec_dispatch);
 	INIT_WORK(&nvec->tx_work, nvec_request_master);
 
-	err = devm_gpio_request_one(&pdev->dev, nvec->gpio, GPIOF_OUT_INIT_HIGH,
-					"nvec gpio");
-	if (err < 0) {
+	ret = devm_gpio_request_one(&client->dev, nvec->gpio,
+			GPIOF_OUT_INIT_HIGH,
+			"nvec gpio");
+	if (ret < 0) {
 		dev_err(nvec->dev, "couldn't request gpio\n");
 		return -ENODEV;
 	}
 
-	err = devm_request_irq(&pdev->dev, nvec->irq, nvec_interrupt, 0,
-				"nvec", nvec);
-	if (err) {
-		dev_err(nvec->dev, "couldn't request irq\n");
-		return -ENODEV;
-	}
-	disable_irq(nvec->irq);
-
-	tegra_init_i2c_slave(nvec);
-
 	/* enable event reporting */
 	nvec_toggle_global_events(nvec, true);
 
@@ -907,12 +753,13 @@ static int tegra_nvec_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static int tegra_nvec_remove(struct platform_device *pdev)
+
+static int nvec_remove(struct i2c_client *client)
 {
-	struct nvec_chip *nvec = platform_get_drvdata(pdev);
+	struct nvec_chip *nvec = i2c_get_clientdata(client);
 
 	nvec_toggle_global_events(nvec, false);
-	mfd_remove_devices(nvec->dev);
+	/* TODO: mfd_remove_devices(nvec->dev); ??? */
 	nvec_unregister_notifier(nvec, &nvec->nvec_status_notifier);
 	cancel_work_sync(&nvec->rx_work);
 	cancel_work_sync(&nvec->tx_work);
@@ -938,8 +785,6 @@ static int nvec_suspend(struct device *dev)
 	msg = nvec_write_sync(nvec, ap_suspend, sizeof(ap_suspend));
 	nvec_msg_free(nvec, msg);
 
-	nvec_disable_i2c_slave(nvec);
-
 	return 0;
 }
 
@@ -949,7 +794,6 @@ static int nvec_resume(struct device *dev)
 	struct nvec_chip *nvec = platform_get_drvdata(pdev);
 
 	dev_dbg(nvec->dev, "resuming\n");
-	tegra_init_i2c_slave(nvec);
 	nvec_toggle_global_events(nvec, true);
 
 	return 0;
@@ -965,9 +809,16 @@ static const struct of_device_id nvidia_nvec_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, nvidia_nvec_of_match);
 
-static struct platform_driver nvec_device_driver = {
-	.probe   = tegra_nvec_probe,
-	.remove  = tegra_nvec_remove,
+static const struct i2c_device_id nvidia_nvec_i2c_table[] = {
+	{ "nvec", 0 },
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, nvidia_nvec_i2c_table);
+
+static struct i2c_driver i2c_nvec_device_driver = {
+	.probe   = nvec_probe,
+	.remove  = nvec_remove,
+	.id_table = nvidia_nvec_i2c_table,
 	.driver  = {
 		.name = "nvec",
 		.pm = &nvec_pm_ops,
@@ -975,9 +826,9 @@ static struct platform_driver nvec_device_driver = {
 	}
 };
 
-module_platform_driver(nvec_device_driver);
+module_i2c_driver(i2c_nvec_device_driver);
 
-MODULE_ALIAS("platform:nvec");
+MODULE_ALIAS("i2c:nvec");
 MODULE_DESCRIPTION("NVIDIA compliant embedded controller interface");
 MODULE_AUTHOR("Marc Dietrich <marvin24@....de>");
 MODULE_LICENSE("GPL");
diff --git a/drivers/staging/nvec/nvec.h b/drivers/staging/nvec/nvec.h
index e271375..5e7e17c 100644
--- a/drivers/staging/nvec/nvec.h
+++ b/drivers/staging/nvec/nvec.h
@@ -56,6 +56,13 @@ enum nvec_event_size {
 	NVEC_VAR_SIZE,
 };
 
+enum nvec_state {
+	ST_NONE,
+	ST_RX,
+	ST_TX,
+	ST_TRANS_START,
+};
+
 /**
  * enum nvec_msg_type - The type of a message
  * @NVEC_SYS: A system request/response
@@ -107,11 +114,6 @@ struct nvec_msg {
  * struct nvec_chip - A single connection to an NVIDIA Embedded controller
  * @dev: The device
  * @gpio: The same as for &struct nvec_platform_data
- * @irq: The IRQ of the I2C device
- * @i2c_addr: The address of the I2C slave
- * @base: The base of the memory mapped region of the I2C device
- * @i2c_clk: The clock of the I2C device
- * @rst: The reset of the I2C device
  * @notifier_list: Notifiers to be called on received messages, see
  *                 nvec_register_notifier()
  * @rx_data: Received messages that have to be processed
@@ -137,11 +139,6 @@ struct nvec_msg {
 struct nvec_chip {
 	struct device *dev;
 	int gpio;
-	int irq;
-	int i2c_addr;
-	void __iomem *base;
-	struct clk *i2c_clk;
-	struct reset_control *rst;
 	struct atomic_notifier_head notifier_list;
 	struct list_head rx_data, tx_data;
 	struct notifier_block nvec_status_notifier;
-- 
1.9.1

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