i2c: efm32: new bus driver

This was tested on a EFM32GG-DK3750 devboard that has a temperature
sensor and an eeprom on its i2c bus.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/devicetree/bindings/i2c/i2c-efm32.txt

+* Energymicro efm32 i2c controller
+
+Required properties :
+
+ - reg : Offset and length of the register set for the device
+ - compatible : should be "efm32,i2c"
+ - interrupts : the interrupt number
+ - clocks : reference to the module clock
+
+Recommended properties :
+
+ - clock-frequency : maximal I2C bus clock frequency in Hz.
+ - efm32,location : Decides the location of the USART I/O pins.
+   Allowed range : [0 .. 6]
+
+Example:
+	i2c0: i2c@4000a000 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		compatible = "efm32,i2c";
+		reg = <0x4000a000 0x400>;
+		interrupts = <9>;
+		clocks = <&cmu clk_HFPERCLKI2C0>;
+		clock-frequency = <100000>;
+		status = "disabled";
+		efm32,location = <3>;
+
+		eeprom@50 {
+			compatible = "microchip,24c02";
+			reg = <0x50>;
+			pagesize = <16>;
+		};
+	};
+

drivers/i2c/busses/Kconfig

@@ -433,6 +433,13 @@ config I2C_DESIGNWARE_PCI
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-designware-pci.
 
+config I2C_EFM32
+	tristate "EFM32 I2C controller"
+	depends on ARCH_EFM32 || COMPILE_TEST
+	help
+	  This driver supports the i2c block found in Energy Micro's EFM32
+	  SoCs.
+
 config I2C_EG20T
 	tristate "Intel EG20T PCH/LAPIS Semicon IOH(ML7213/ML7223/ML7831) I2C"
 	depends on PCI

drivers/i2c/busses/Makefile

@@ -41,6 +41,7 @@ obj-$(CONFIG_I2C_DESIGNWARE_PLATFORM)	+= i2c-designware-platform.o
 i2c-designware-platform-objs := i2c-designware-platdrv.o
 obj-$(CONFIG_I2C_DESIGNWARE_PCI)	+= i2c-designware-pci.o
 i2c-designware-pci-objs := i2c-designware-pcidrv.o
+obj-$(CONFIG_I2C_EFM32)		+= i2c-efm32.o
 obj-$(CONFIG_I2C_EG20T)		+= i2c-eg20t.o
 obj-$(CONFIG_I2C_EXYNOS5)	+= i2c-exynos5.o
 obj-$(CONFIG_I2C_GPIO)		+= i2c-gpio.o

drivers/i2c/busses/i2c-efm32.c

+/*
+ * Copyright (C) 2014 Uwe Kleine-Koenig for Pengutronix
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+
+#define DRIVER_NAME "efm32-i2c"
+
+#define MASK_VAL(mask, val)		((val << __ffs(mask)) & mask)
+
+#define REG_CTRL		0x00
+#define REG_CTRL_EN			0x00001
+#define REG_CTRL_SLAVE			0x00002
+#define REG_CTRL_AUTOACK		0x00004
+#define REG_CTRL_AUTOSE			0x00008
+#define REG_CTRL_AUTOSN			0x00010
+#define REG_CTRL_ARBDIS			0x00020
+#define REG_CTRL_GCAMEN			0x00040
+#define REG_CTRL_CLHR__MASK		0x00300
+#define REG_CTRL_BITO__MASK		0x03000
+#define REG_CTRL_BITO_OFF		0x00000
+#define REG_CTRL_BITO_40PCC		0x01000
+#define REG_CTRL_BITO_80PCC		0x02000
+#define REG_CTRL_BITO_160PCC		0x03000
+#define REG_CTRL_GIBITO			0x08000
+#define REG_CTRL_CLTO__MASK		0x70000
+#define REG_CTRL_CLTO_OFF		0x00000
+
+#define REG_CMD			0x04
+#define REG_CMD_START			0x00001
+#define REG_CMD_STOP			0x00002
+#define REG_CMD_ACK			0x00004
+#define REG_CMD_NACK			0x00008
+#define REG_CMD_CONT			0x00010
+#define REG_CMD_ABORT			0x00020
+#define REG_CMD_CLEARTX			0x00040
+#define REG_CMD_CLEARPC			0x00080
+
+#define REG_STATE		0x08
+#define REG_STATE_BUSY			0x00001
+#define REG_STATE_MASTER		0x00002
+#define REG_STATE_TRANSMITTER		0x00004
+#define REG_STATE_NACKED		0x00008
+#define REG_STATE_BUSHOLD		0x00010
+#define REG_STATE_STATE__MASK		0x000e0
+#define REG_STATE_STATE_IDLE		0x00000
+#define REG_STATE_STATE_WAIT		0x00020
+#define REG_STATE_STATE_START		0x00040
+#define REG_STATE_STATE_ADDR		0x00060
+#define REG_STATE_STATE_ADDRACK		0x00080
+#define REG_STATE_STATE_DATA		0x000a0
+#define REG_STATE_STATE_DATAACK		0x000c0
+
+#define REG_STATUS		0x0c
+#define REG_STATUS_PSTART		0x00001
+#define REG_STATUS_PSTOP		0x00002
+#define REG_STATUS_PACK			0x00004
+#define REG_STATUS_PNACK		0x00008
+#define REG_STATUS_PCONT		0x00010
+#define REG_STATUS_PABORT		0x00020
+#define REG_STATUS_TXC			0x00040
+#define REG_STATUS_TXBL			0x00080
+#define REG_STATUS_RXDATAV		0x00100
+
+#define REG_CLKDIV		0x10
+#define REG_CLKDIV_DIV__MASK		0x001ff
+#define REG_CLKDIV_DIV(div)		MASK_VAL(REG_CLKDIV_DIV__MASK, (div))
+
+#define REG_SADDR		0x14
+#define REG_SADDRMASK		0x18
+#define REG_RXDATA		0x1c
+#define REG_RXDATAP		0x20
+#define REG_TXDATA		0x24
+#define REG_IF			0x28
+#define REG_IF_START			0x00001
+#define REG_IF_RSTART			0x00002
+#define REG_IF_ADDR			0x00004
+#define REG_IF_TXC			0x00008
+#define REG_IF_TXBL			0x00010
+#define REG_IF_RXDATAV			0x00020
+#define REG_IF_ACK			0x00040
+#define REG_IF_NACK			0x00080
+#define REG_IF_MSTOP			0x00100
+#define REG_IF_ARBLOST			0x00200
+#define REG_IF_BUSERR			0x00400
+#define REG_IF_BUSHOLD			0x00800
+#define REG_IF_TXOF			0x01000
+#define REG_IF_RXUF			0x02000
+#define REG_IF_BITO			0x04000
+#define REG_IF_CLTO			0x08000
+#define REG_IF_SSTOP			0x10000
+
+#define REG_IFS			0x2c
+#define REG_IFC			0x30
+#define REG_IFC__MASK			0x1ffcf
+
+#define REG_IEN			0x34
+
+#define REG_ROUTE		0x38
+#define REG_ROUTE_SDAPEN		0x00001
+#define REG_ROUTE_SCLPEN		0x00002
+#define REG_ROUTE_LOCATION__MASK	0x00700
+#define REG_ROUTE_LOCATION(n)		MASK_VAL(REG_ROUTE_LOCATION__MASK, (n))
+
+struct efm32_i2c_ddata {
+	struct i2c_adapter adapter;
+
+	struct clk *clk;
+	void __iomem *base;
+	unsigned int irq;
+	u8 location;
+	unsigned long frequency;
+
+	/* transfer data */
+	struct completion done;
+	struct i2c_msg *msgs;
+	size_t num_msgs;
+	size_t current_word, current_msg;
+	int retval;
+};
+
+static u32 efm32_i2c_read32(struct efm32_i2c_ddata *ddata, unsigned offset)
+{
+	return readl(ddata->base + offset);
+}
+
+static void efm32_i2c_write32(struct efm32_i2c_ddata *ddata,
+		unsigned offset, u32 value)
+{
+	writel(value, ddata->base + offset);
+}
+
+static void efm32_i2c_send_next_msg(struct efm32_i2c_ddata *ddata)
+{
+	struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
+
+	efm32_i2c_write32(ddata, REG_CMD, REG_CMD_START);
+	efm32_i2c_write32(ddata, REG_TXDATA, cur_msg->addr << 1 |
+			(cur_msg->flags & I2C_M_RD ? 1 : 0));
+}
+
+static void efm32_i2c_send_next_byte(struct efm32_i2c_ddata *ddata)
+{
+	struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
+
+	if (ddata->current_word >= cur_msg->len) {
+		/* cur_msg completely transferred */
+		ddata->current_word = 0;
+		ddata->current_msg += 1;
+
+		if (ddata->current_msg >= ddata->num_msgs) {
+			efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
+			complete(&ddata->done);
+		} else {
+			efm32_i2c_send_next_msg(ddata);
+		}
+	} else {
+		efm32_i2c_write32(ddata, REG_TXDATA,
+				cur_msg->buf[ddata->current_word++]);
+	}
+}
+
+static void efm32_i2c_recv_next_byte(struct efm32_i2c_ddata *ddata)
+{
+	struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
+
+	cur_msg->buf[ddata->current_word] = efm32_i2c_read32(ddata, REG_RXDATA);
+	ddata->current_word += 1;
+	if (ddata->current_word >= cur_msg->len) {
+		/* cur_msg completely transferred */
+		ddata->current_word = 0;
+		ddata->current_msg += 1;
+
+		efm32_i2c_write32(ddata, REG_CMD, REG_CMD_NACK);
+
+		if (ddata->current_msg >= ddata->num_msgs) {
+			efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
+			complete(&ddata->done);
+		} else {
+			efm32_i2c_send_next_msg(ddata);
+		}
+	} else {
+		efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ACK);
+	}
+}
+
+static irqreturn_t efm32_i2c_irq(int irq, void *dev_id)
+{
+	struct efm32_i2c_ddata *ddata = dev_id;
+	struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg];
+	u32 irqflag = efm32_i2c_read32(ddata, REG_IF);
+	u32 state = efm32_i2c_read32(ddata, REG_STATE);
+
+	efm32_i2c_write32(ddata, REG_IFC, irqflag & REG_IFC__MASK);
+
+	switch (state & REG_STATE_STATE__MASK) {
+	case REG_STATE_STATE_IDLE:
+		/* arbitration lost? */
+		ddata->retval = -EAGAIN;
+		complete(&ddata->done);
+		break;
+	case REG_STATE_STATE_WAIT:
+		/*
+		 * huh, this shouldn't happen.
+		 * Reset hardware state and get out
+		 */
+		ddata->retval = -EIO;
+		efm32_i2c_write32(ddata, REG_CMD,
+				REG_CMD_STOP | REG_CMD_ABORT |
+				REG_CMD_CLEARTX | REG_CMD_CLEARPC);
+		complete(&ddata->done);
+		break;
+	case REG_STATE_STATE_START:
+		/* "caller" is expected to send an address */
+		break;
+	case REG_STATE_STATE_ADDR:
+		/* wait for Ack or NAck of slave */
+		break;
+	case REG_STATE_STATE_ADDRACK:
+		if (state & REG_STATE_NACKED) {
+			efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
+			ddata->retval = -ENXIO;
+			complete(&ddata->done);
+		} else if (cur_msg->flags & I2C_M_RD) {
+			/* wait for slave to send first data byte */
+		} else {
+			efm32_i2c_send_next_byte(ddata);
+		}
+		break;
+	case REG_STATE_STATE_DATA:
+		if (cur_msg->flags & I2C_M_RD) {
+			efm32_i2c_recv_next_byte(ddata);
+		} else {
+			/* wait for Ack or Nack of slave */
+		}
+		break;
+	case REG_STATE_STATE_DATAACK:
+		if (state & REG_STATE_NACKED) {
+			efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP);
+			complete(&ddata->done);
+		} else {
+			efm32_i2c_send_next_byte(ddata);
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int efm32_i2c_master_xfer(struct i2c_adapter *adap,
+		struct i2c_msg *msgs, int num)
+{
+	struct efm32_i2c_ddata *ddata = i2c_get_adapdata(adap);
+	int ret;
+
+	if (ddata->msgs)
+		return -EBUSY;
+
+	ddata->msgs = msgs;
+	ddata->num_msgs = num;
+	ddata->current_word = 0;
+	ddata->current_msg = 0;
+	ddata->retval = -EIO;
+
+	reinit_completion(&ddata->done);
+
+	dev_dbg(&ddata->adapter.dev, "state: %08x, status: %08x\n",
+			efm32_i2c_read32(ddata, REG_STATE),
+			efm32_i2c_read32(ddata, REG_STATUS));
+
+	efm32_i2c_send_next_msg(ddata);
+
+	wait_for_completion(&ddata->done);
+
+	if (ddata->current_msg >= ddata->num_msgs)
+		ret = ddata->num_msgs;
+	else
+		ret = ddata->retval;
+
+	return ret;
+}
+
+static u32 efm32_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm efm32_i2c_algo = {
+	.master_xfer = efm32_i2c_master_xfer,
+	.functionality = efm32_i2c_functionality,
+};
+
+static u32 efm32_i2c_get_configured_location(struct efm32_i2c_ddata *ddata)
+{
+	u32 reg = efm32_i2c_read32(ddata, REG_ROUTE);
+
+	return (reg & REG_ROUTE_LOCATION__MASK) >>
+		__ffs(REG_ROUTE_LOCATION__MASK);
+}
+
+static int efm32_i2c_probe(struct platform_device *pdev)
+{
+	struct efm32_i2c_ddata *ddata;
+	struct resource *res;
+	unsigned long rate;
+	struct device_node *np = pdev->dev.of_node;
+	u32 location, frequency;
+	int ret;
+	u32 clkdiv;
+
+	if (!np)
+		return -EINVAL;
+
+	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata) {
+		dev_dbg(&pdev->dev, "failed to allocate private data\n");
+		return -ENOMEM;
+	}
+	platform_set_drvdata(pdev, ddata);
+
+	init_completion(&ddata->done);
+	strlcpy(ddata->adapter.name, pdev->name, sizeof(ddata->adapter.name));
+	ddata->adapter.owner = THIS_MODULE;
+	ddata->adapter.algo = &efm32_i2c_algo;
+	ddata->adapter.dev.parent = &pdev->dev;
+	ddata->adapter.dev.of_node = pdev->dev.of_node;
+	i2c_set_adapdata(&ddata->adapter, ddata);
+
+	ddata->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(ddata->clk)) {
+		ret = PTR_ERR(ddata->clk);
+		dev_err(&pdev->dev, "failed to get clock: %d\n", ret);
+		return ret;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "failed to determine base address\n");
+		return -ENODEV;
+	}
+
+	if (resource_size(res) < 0x42) {
+		dev_err(&pdev->dev, "memory resource too small\n");
+		return -EINVAL;
+	}
+
+	ddata->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ddata->base))
+		return PTR_ERR(ddata->base);
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret <= 0) {
+		dev_err(&pdev->dev, "failed to get irq (%d)\n", ret);
+		if (!ret)
+			ret = -EINVAL;
+		return ret;
+	}
+
+	ddata->irq = ret;
+
+	ret = clk_prepare_enable(ddata->clk);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to enable clock (%d)\n", ret);
+		return ret;
+	}
+
+	ret = of_property_read_u32(np, "efm32,location", &location);
+	if (!ret) {
+		dev_dbg(&pdev->dev, "using location %u\n", location);
+	} else {
+		/* default to location configured in hardware */
+		location = efm32_i2c_get_configured_location(ddata);
+
+		dev_info(&pdev->dev, "fall back to location %u\n", location);
+	}
+
+	ddata->location = location;
+
+	ret = of_property_read_u32(np, "clock-frequency", &frequency);
+	if (!ret) {
+		dev_dbg(&pdev->dev, "using frequency %u\n", frequency);
+	} else {
+		frequency = 100000;
+		dev_info(&pdev->dev, "defaulting to 100 kHz\n");
+	}
+	ddata->frequency = frequency;
+
+	rate = clk_get_rate(ddata->clk);
+	if (!rate) {
+		dev_err(&pdev->dev, "there is no input clock available\n");
+		ret = -EINVAL;
+		goto err_disable_clk;
+	}
+	clkdiv = DIV_ROUND_UP(rate, 8 * ddata->frequency) - 1;
+	if (clkdiv >= 0x200) {
+		dev_err(&pdev->dev,
+				"input clock too fast (%lu) to divide down to bus freq (%lu)",
+				rate, ddata->frequency);
+		ret = -EINVAL;
+		goto err_disable_clk;
+	}
+
+	dev_dbg(&pdev->dev, "input clock = %lu, bus freq = %lu, clkdiv = %lu\n",
+			rate, ddata->frequency, (unsigned long)clkdiv);
+	efm32_i2c_write32(ddata, REG_CLKDIV, REG_CLKDIV_DIV(clkdiv));
+
+	efm32_i2c_write32(ddata, REG_ROUTE, REG_ROUTE_SDAPEN |
+			REG_ROUTE_SCLPEN |
+			REG_ROUTE_LOCATION(ddata->location));
+
+	efm32_i2c_write32(ddata, REG_CTRL, REG_CTRL_EN |
+			REG_CTRL_BITO_160PCC | 0 * REG_CTRL_GIBITO);
+
+	efm32_i2c_write32(ddata, REG_IFC, REG_IFC__MASK);
+	efm32_i2c_write32(ddata, REG_IEN, REG_IF_TXC | REG_IF_ACK | REG_IF_NACK
+			| REG_IF_ARBLOST | REG_IF_BUSERR | REG_IF_RXDATAV);
+
+	/* to make bus idle */
+	efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ABORT);
+
+	ret = request_irq(ddata->irq, efm32_i2c_irq, 0, DRIVER_NAME, ddata);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to request irq (%d)\n", ret);
+		return ret;
+	}
+
+	ret = i2c_add_adapter(&ddata->adapter);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add i2c adapter (%d)\n", ret);
+		free_irq(ddata->irq, ddata);
+
+err_disable_clk:
+		clk_disable_unprepare(ddata->clk);
+	}
+	return ret;
+}
+
+static int efm32_i2c_remove(struct platform_device *pdev)
+{
+	struct efm32_i2c_ddata *ddata = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&ddata->adapter);
+	free_irq(ddata->irq, ddata);
+	clk_disable_unprepare(ddata->clk);
+
+	return 0;
+}
+
+static const struct of_device_id efm32_i2c_dt_ids[] = {
+	{
+		.compatible = "energymicro,efm32-i2c",
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, efm32_i2c_dt_ids);
+
+static struct platform_driver efm32_i2c_driver = {
+	.probe = efm32_i2c_probe,
+	.remove = efm32_i2c_remove,
+
+	.driver = {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = efm32_i2c_dt_ids,
+	},
+};
+module_platform_driver(efm32_i2c_driver);
+
+MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
+MODULE_DESCRIPTION("EFM32 i2c driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:" DRIVER_NAME);