1 files changed, 183 insertions, 55 deletions

diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
index cd07a69e2e93..0d7e2654a534 100644
--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -1,23 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
- * BCM2835 master mode driver
- *
- * This software is licensed under the terms of the GNU General Public
- * License version 2, as published by the Free Software Foundation, and
- * may be copied, distributed, and modified under those terms.
- *
- * 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.
+ * BCM2835 I2C controller driver
  */
 
 #include <linux/clk.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
 #include <linux/completion.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 
@@ -28,6 +23,11 @@
 #define BCM2835_I2C_FIFO	0x10
 #define BCM2835_I2C_DIV		0x14
 #define BCM2835_I2C_DEL		0x18
+/*
+ * 16-bit field for the number of SCL cycles to wait after rising SCL
+ * before deciding the target is not responding. 0 disables the
+ * timeout detection.
+ */
 #define BCM2835_I2C_CLKT	0x1c
 
 #define BCM2835_I2C_C_READ	BIT(0)
@@ -50,18 +50,20 @@
 #define BCM2835_I2C_S_CLKT	BIT(9)
 #define BCM2835_I2C_S_LEN	BIT(10) /* Fake bit for SW error reporting */
 
+#define BCM2835_I2C_FEDL_SHIFT	16
+#define BCM2835_I2C_REDL_SHIFT	0
+
 #define BCM2835_I2C_CDIV_MIN	0x0002
 #define BCM2835_I2C_CDIV_MAX	0xFFFE
 
 struct bcm2835_i2c_dev {
 	struct device *dev;
 	void __iomem *regs;
-	struct clk *clk;
 	int irq;
-	u32 bus_clk_rate;
 	struct i2c_adapter adapter;
 	struct completion completion;
 	struct i2c_msg *curr_msg;
+	struct clk *bus_clk;
 	int num_msgs;
 	u32 msg_err;
 	u8 *msg_buf;
@@ -79,12 +81,17 @@ static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg)
 	return readl(i2c_dev->regs + reg);
 }
 
-static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev)
+#define to_clk_bcm2835_i2c(_hw) container_of(_hw, struct clk_bcm2835_i2c, hw)
+struct clk_bcm2835_i2c {
+	struct clk_hw hw;
+	struct bcm2835_i2c_dev *i2c_dev;
+};
+
+static int clk_bcm2835_i2c_calc_divider(unsigned long rate,
+				unsigned long parent_rate)
 {
-	u32 divider;
+	u32 divider = DIV_ROUND_UP(parent_rate, rate);
 
-	divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk),
-			       i2c_dev->bus_clk_rate);
 	/*
 	 * Per the datasheet, the register is always interpreted as an even
 	 * number, by rounding down. In other words, the LSB is ignored. So,
@@ -93,16 +100,98 @@ static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev)
 	if (divider & 1)
 		divider++;
 	if ((divider < BCM2835_I2C_CDIV_MIN) ||
-	    (divider > BCM2835_I2C_CDIV_MAX)) {
-		dev_err_ratelimited(i2c_dev->dev, "Invalid clock-frequency\n");
+	    (divider > BCM2835_I2C_CDIV_MAX))
 		return -EINVAL;
-	}
 
-	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider);
+	return divider;
+}
+
+static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long parent_rate)
+{
+	struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw);
+	u32 redl, fedl;
+	u32 divider = clk_bcm2835_i2c_calc_divider(rate, parent_rate);
+
+	if (divider == -EINVAL)
+		return -EINVAL;
+
+	bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DIV, divider);
+
+	/*
+	 * Number of core clocks to wait after falling edge before
+	 * outputting the next data bit.  Note that both FEDL and REDL
+	 * can't be greater than CDIV/2.
+	 */
+	fedl = max(divider / 16, 1u);
+
+	/*
+	 * Number of core clocks to wait after rising edge before
+	 * sampling the next incoming data bit.
+	 */
+	redl = max(divider / 4, 1u);
+
+	bcm2835_i2c_writel(div->i2c_dev, BCM2835_I2C_DEL,
+			   (fedl << BCM2835_I2C_FEDL_SHIFT) |
+			   (redl << BCM2835_I2C_REDL_SHIFT));
+	return 0;
+}
+
+static int clk_bcm2835_i2c_determine_rate(struct clk_hw *hw,
+					  struct clk_rate_request *req)
+{
+	u32 divider = clk_bcm2835_i2c_calc_divider(req->rate, req->best_parent_rate);
+
+	req->rate = DIV_ROUND_UP(req->best_parent_rate, divider);
 
 	return 0;
 }
 
+static unsigned long clk_bcm2835_i2c_recalc_rate(struct clk_hw *hw,
+						unsigned long parent_rate)
+{
+	struct clk_bcm2835_i2c *div = to_clk_bcm2835_i2c(hw);
+	u32 divider = bcm2835_i2c_readl(div->i2c_dev, BCM2835_I2C_DIV);
+
+	return DIV_ROUND_UP(parent_rate, divider);
+}
+
+static const struct clk_ops clk_bcm2835_i2c_ops = {
+	.set_rate = clk_bcm2835_i2c_set_rate,
+	.determine_rate = clk_bcm2835_i2c_determine_rate,
+	.recalc_rate = clk_bcm2835_i2c_recalc_rate,
+};
+
+static struct clk *bcm2835_i2c_register_div(struct device *dev,
+					struct clk *mclk,
+					struct bcm2835_i2c_dev *i2c_dev)
+{
+	struct clk_init_data init;
+	struct clk_bcm2835_i2c *priv;
+	char name[32];
+	const char *mclk_name;
+
+	snprintf(name, sizeof(name), "%s_div", dev_name(dev));
+
+	mclk_name = __clk_get_name(mclk);
+
+	init.ops = &clk_bcm2835_i2c_ops;
+	init.name = name;
+	init.parent_names = (const char* []) { mclk_name };
+	init.num_parents = 1;
+	init.flags = 0;
+
+	priv = devm_kzalloc(dev, sizeof(struct clk_bcm2835_i2c), GFP_KERNEL);
+	if (priv == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	priv->hw.init = &init;
+	priv->i2c_dev = i2c_dev;
+
+	clk_hw_register_clkdev(&priv->hw, "div", dev_name(dev));
+	return devm_clk_register(dev, &priv->hw);
+}
+
 static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev)
 {
 	u32 val;
@@ -136,7 +225,7 @@ static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev)
 /*
  * Repeated Start Condition (Sr)
  * The BCM2835 ARM Peripherals datasheet mentions a way to trigger a Sr when it
- * talks about reading from a slave with 10 bit address. This is achieved by
+ * talks about reading from a target with 10 bit address. This is achieved by
  * issuing a write, poll the I2CS.TA flag and wait for it to be set, and then
  * issue a read.
  * A comment in https://github.com/raspberrypi/linux/issues/254 shows how the
@@ -172,6 +261,15 @@ static void bcm2835_i2c_start_transfer(struct bcm2835_i2c_dev *i2c_dev)
 	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c);
 }
 
+static void bcm2835_i2c_finish_transfer(struct bcm2835_i2c_dev *i2c_dev)
+{
+	i2c_dev->curr_msg = NULL;
+	i2c_dev->num_msgs = 0;
+
+	i2c_dev->msg_buf = NULL;
+	i2c_dev->msg_buf_remaining = 0;
+}
+
 /*
  * Note about I2C_C_CLEAR on error:
  * The I2C_C_CLEAR on errors will take some time to resolve -- if you were in
@@ -251,7 +349,7 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 {
 	struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
 	unsigned long time_left;
-	int i, ret;
+	int i;
 
 	for (i = 0; i < (num - 1); i++)
 		if (msgs[i].flags & I2C_M_RD) {
@@ -260,10 +358,6 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 			return -EOPNOTSUPP;
 		}
 
-	ret = bcm2835_i2c_set_divider(i2c_dev);
-	if (ret)
-		return ret;
-
 	i2c_dev->curr_msg = msgs;
 	i2c_dev->num_msgs = num;
 	reinit_completion(&i2c_dev->completion);
@@ -272,10 +366,12 @@ static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 
 	time_left = wait_for_completion_timeout(&i2c_dev->completion,
 						adap->timeout);
+
+	bcm2835_i2c_finish_transfer(i2c_dev);
+
 	if (!time_left) {
 		bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C,
 				   BCM2835_I2C_C_CLEAR);
-		dev_err(i2c_dev->dev, "i2c transfer timed out\n");
 		return -ETIMEDOUT;
 	}
 
@@ -296,13 +392,13 @@ static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
 }
 
 static const struct i2c_algorithm bcm2835_i2c_algo = {
-	.master_xfer	= bcm2835_i2c_xfer,
-	.functionality	= bcm2835_i2c_func,
+	.xfer = bcm2835_i2c_xfer,
+	.functionality = bcm2835_i2c_func,
 };
 
 /*
- * This HW was reported to have problems with clock stretching:
- * http://www.advamation.com/knowhow/raspberrypi/rpi-i2c-bug.html
+ * The BCM2835 was reported to have problems with clock stretching:
+ * https://www.advamation.com/knowhow/raspberrypi/rpi-i2c-bug.html
  * https://www.raspberrypi.org/forums/viewtopic.php?p=146272
  */
 static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
@@ -312,9 +408,10 @@ static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
 static int bcm2835_i2c_probe(struct platform_device *pdev)
 {
 	struct bcm2835_i2c_dev *i2c_dev;
-	struct resource *mem, *irq;
 	int ret;
 	struct i2c_adapter *adap;
+	struct clk *mclk;
+	u32 bus_clk_rate;
 
 	i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
 	if (!i2c_dev)
@@ -323,71 +420,102 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
 	i2c_dev->dev = &pdev->dev;
 	init_completion(&i2c_dev->completion);
 
-	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	i2c_dev->regs = devm_ioremap_resource(&pdev->dev, mem);
+	i2c_dev->regs = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
 	if (IS_ERR(i2c_dev->regs))
 		return PTR_ERR(i2c_dev->regs);
 
-	i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(i2c_dev->clk)) {
-		if (PTR_ERR(i2c_dev->clk) != -EPROBE_DEFER)
-			dev_err(&pdev->dev, "Could not get clock\n");
-		return PTR_ERR(i2c_dev->clk);
-	}
+	mclk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(mclk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(mclk),
+				     "Could not get clock\n");
+
+	i2c_dev->bus_clk = bcm2835_i2c_register_div(&pdev->dev, mclk, i2c_dev);
+
+	if (IS_ERR(i2c_dev->bus_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(i2c_dev->bus_clk),
+				     "Could not register clock\n");
 
 	ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
-				   &i2c_dev->bus_clk_rate);
+				   &bus_clk_rate);
 	if (ret < 0) {
 		dev_warn(&pdev->dev,
 			 "Could not read clock-frequency property\n");
-		i2c_dev->bus_clk_rate = 100000;
+		bus_clk_rate = I2C_MAX_STANDARD_MODE_FREQ;
+	}
+
+	ret = clk_set_rate_exclusive(i2c_dev->bus_clk, bus_clk_rate);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret,
+				     "Could not set clock frequency\n");
+
+	ret = clk_prepare_enable(i2c_dev->bus_clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Couldn't prepare clock");
+		goto err_put_exclusive_rate;
 	}
 
-	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
-	if (!irq) {
-		dev_err(&pdev->dev, "No IRQ resource\n");
-		return -ENODEV;
+	i2c_dev->irq = platform_get_irq(pdev, 0);
+	if (i2c_dev->irq < 0) {
+		ret = i2c_dev->irq;
+		goto err_disable_unprepare_clk;
 	}
-	i2c_dev->irq = irq->start;
 
 	ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED,
 			  dev_name(&pdev->dev), i2c_dev);
 	if (ret) {
 		dev_err(&pdev->dev, "Could not request IRQ\n");
-		return -ENODEV;
+		goto err_disable_unprepare_clk;
 	}
 
 	adap = &i2c_dev->adapter;
 	i2c_set_adapdata(adap, i2c_dev);
 	adap->owner = THIS_MODULE;
 	adap->class = I2C_CLASS_DEPRECATED;
-	strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name));
+	snprintf(adap->name, sizeof(adap->name), "bcm2835 (%s)",
+		 of_node_full_name(pdev->dev.of_node));
 	adap->algo = &bcm2835_i2c_algo;
 	adap->dev.parent = &pdev->dev;
 	adap->dev.of_node = pdev->dev.of_node;
-	adap->quirks = &bcm2835_i2c_quirks;
+	adap->quirks = of_device_get_match_data(&pdev->dev);
 
+	/*
+	 * Disable the hardware clock stretching timeout. SMBUS
+	 * specifies a limit for how long the device can stretch the
+	 * clock, but core I2C doesn't.
+	 */
+	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_CLKT, 0);
 	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0);
 
 	ret = i2c_add_adapter(adap);
 	if (ret)
-		free_irq(i2c_dev->irq, i2c_dev);
+		goto err_free_irq;
+
+	return 0;
+
+err_free_irq:
+	free_irq(i2c_dev->irq, i2c_dev);
+err_disable_unprepare_clk:
+	clk_disable_unprepare(i2c_dev->bus_clk);
+err_put_exclusive_rate:
+	clk_rate_exclusive_put(i2c_dev->bus_clk);
 
 	return ret;
 }
 
-static int bcm2835_i2c_remove(struct platform_device *pdev)
+static void bcm2835_i2c_remove(struct platform_device *pdev)
 {
 	struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
 
+	clk_rate_exclusive_put(i2c_dev->bus_clk);
+	clk_disable_unprepare(i2c_dev->bus_clk);
+
 	free_irq(i2c_dev->irq, i2c_dev);
 	i2c_del_adapter(&i2c_dev->adapter);
-
-	return 0;
 }
 
 static const struct of_device_id bcm2835_i2c_of_match[] = {
-	{ .compatible = "brcm,bcm2835-i2c" },
+	{ .compatible = "brcm,bcm2711-i2c" },
+	{ .compatible = "brcm,bcm2835-i2c", .data = &bcm2835_i2c_quirks },
 	{},
 };
 MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match);