[PATCH 1/2] i2c: add i2c-lpc2k driver
Joachim Eastwood
manabian at gmail.com
Sun Jul 12 15:47:21 PDT 2015
Add support for the I2C controller found on several NXP devices
including LPC2xxx, LPC178x/7x and LPC18xx/43xx. The controller
is implemented as a state machine and the driver act upon the
state changes when the bus is accessed.
The I2C controller supports master/slave operation, bus
arbitration, programmable clock rate, and speeds up to 1 Mbit/s.
Signed-off-by: Joachim Eastwood <manabian at gmail.com>
---
drivers/i2c/busses/Kconfig | 10 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-lpc2k.c | 551 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 562 insertions(+)
create mode 100644 drivers/i2c/busses/i2c-lpc2k.c
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 35ac23768ce9..a880c82bed3d 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -612,6 +612,16 @@ config I2C_KEMPLD
This driver can also be built as a module. If so, the module
will be called i2c-kempld.
+config I2C_LPC2K
+ tristate "I2C bus support for NXP LPC2K/LPC178x/18xx/43xx"
+ depends on OF && (ARCH_LPC18XX || COMPILE_TEST)
+ help
+ This driver supports the I2C interface found several NXP
+ devices including LPC2xxx, LPC178x/7x and LPC18xx/43xx.
+
+ This driver can also be built as a module. If so, the module
+ will be called i2c-lpc2k.
+
config I2C_MESON
tristate "Amlogic Meson I2C controller"
depends on ARCH_MESON
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index e5f537c80da0..65b84097e665 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_I2C_IMX) += i2c-imx.o
obj-$(CONFIG_I2C_IOP3XX) += i2c-iop3xx.o
obj-$(CONFIG_I2C_JZ4780) += i2c-jz4780.o
obj-$(CONFIG_I2C_KEMPLD) += i2c-kempld.o
+obj-$(CONFIG_I2C_LPC2K) += i2c-lpc2k.o
obj-$(CONFIG_I2C_MESON) += i2c-meson.o
obj-$(CONFIG_I2C_MPC) += i2c-mpc.o
obj-$(CONFIG_I2C_MT65XX) += i2c-mt65xx.o
diff --git a/drivers/i2c/busses/i2c-lpc2k.c b/drivers/i2c/busses/i2c-lpc2k.c
new file mode 100644
index 000000000000..7bcbecc8dabe
--- /dev/null
+++ b/drivers/i2c/busses/i2c-lpc2k.c
@@ -0,0 +1,551 @@
+/*
+ * Copyright (C) 2011 NXP Semiconductors
+ *
+ * Code portions referenced from the i2x-pxa and i2c-pnx drivers
+ *
+ * Make SMBus byte and word transactions work on LPC178x/7x
+ * Copyright (c) 2012
+ * Alexander Potashev, Emcraft Systems, aspotashev at emcraft.com
+ * Anton Protopopov, Emcraft Systems, antonp at emcraft.com
+ *
+ * Copyright (C) 2015 Joachim Eastwood <manabian at gmail.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.
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+
+/* LPC24xx register offsets and bits */
+#define LPC24XX_I2CONSET 0x00
+#define LPC24XX_I2STAT 0x04
+#define LPC24XX_I2DAT 0x08
+#define LPC24XX_I2ADDR 0x0c
+#define LPC24XX_I2SCLH 0x10
+#define LPC24XX_I2SCLL 0x14
+#define LPC24XX_I2CONCLR 0x18
+
+#define LPC24XX_AA BIT(2)
+#define LPC24XX_SI BIT(3)
+#define LPC24XX_STO BIT(4)
+#define LPC24XX_STA BIT(5)
+#define LPC24XX_I2EN BIT(6)
+
+#define LPC24XX_CLEAR_ALL (LPC24XX_AA | LPC24XX_SI | LPC24XX_STO | \
+ LPC24XX_STA | LPC24XX_I2EN)
+
+/* I2C SCL clock has different duty cycle depending on mode */
+#define I2C_STD_MODE_DUTY 46
+#define I2C_FAST_MODE_DUTY 32
+#define I2C_FAST_MODE_PLUS_DUTY 34
+
+/*
+ * 26 possible I2C status codes, but codes applicable only
+ * to master are listed here and used in this driver
+ */
+enum {
+ M_BUS_ERROR = 0x00,
+ M_START = 0x08,
+ M_REPSTART = 0x10,
+ MX_ADDR_W_ACK = 0x18,
+ MX_ADDR_W_NACK = 0x20,
+ MX_DATA_W_ACK = 0x28,
+ MX_DATA_W_NACK = 0x30,
+ M_DATA_ARB_LOST = 0x38,
+ MR_ADDR_R_ACK = 0x40,
+ MR_ADDR_R_NACK = 0x48,
+ MR_DATA_R_ACK = 0x50,
+ MR_DATA_R_NACK = 0x58,
+ M_I2C_IDLE = 0xf8,
+};
+
+struct lpc2k_i2c {
+ void __iomem *reg_base;
+ struct clk *clk;
+ int irq;
+ wait_queue_head_t wait;
+ struct i2c_adapter adap;
+ struct i2c_msg *msg;
+ int msg_idx;
+ int msg_status;
+ int is_last;
+};
+
+static void i2c_lpc2k_reset(struct lpc2k_i2c *i2c)
+{
+ /* Will force clear all statuses */
+ writel(LPC24XX_CLEAR_ALL, i2c->reg_base + LPC24XX_I2CONCLR);
+ writel(0, i2c->reg_base + LPC24XX_I2ADDR);
+ writel(LPC24XX_I2EN, i2c->reg_base + LPC24XX_I2CONSET);
+}
+
+static int i2c_lpc2k_clear_arb(struct lpc2k_i2c *i2c)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(1000);
+
+ /*
+ * If the transfer needs to abort for some reason, we'll try to
+ * force a stop condition to clear any pending bus conditions
+ */
+ writel(LPC24XX_STO, i2c->reg_base + LPC24XX_I2CONSET);
+
+ /* Wait for status change */
+ while (readl(i2c->reg_base + LPC24XX_I2STAT) != M_I2C_IDLE) {
+ if (time_after(jiffies, timeout)) {
+ /* Bus was not idle, try to reset adapter */
+ i2c_lpc2k_reset(i2c);
+ return -EBUSY;
+ }
+
+ cpu_relax();
+ }
+
+ return 0;
+}
+
+static void i2c_lpc2k_pump_msg(struct lpc2k_i2c *i2c)
+{
+ unsigned char data;
+ u32 status;
+
+ /*
+ * I2C in the LPC2xxx series is basically a state machine.
+ * Just run through the steps based on the current status.
+ */
+ status = readl(i2c->reg_base + LPC24XX_I2STAT);
+
+ switch (status) {
+ case M_START:
+ case M_REPSTART:
+ /* Start bit was just sent out, send out addr and dir */
+ data = (i2c->msg->addr << 1);
+ if (i2c->msg->flags & I2C_M_RD)
+ data |= 1;
+
+ writel(data, i2c->reg_base + LPC24XX_I2DAT);
+ writel(LPC24XX_STA, i2c->reg_base + LPC24XX_I2CONCLR);
+
+ dev_dbg(&i2c->adap.dev, "Start sent with addr 0x%02x\n", data);
+ break;
+
+ case MX_ADDR_W_ACK:
+ case MX_DATA_W_ACK:
+ /*
+ * Address or data was sent out with an ACK. If there is more
+ * data to send, send it now
+ */
+ if (i2c->msg_idx < i2c->msg->len) {
+ writel(i2c->msg->buf[i2c->msg_idx],
+ i2c->reg_base + LPC24XX_I2DAT);
+ dev_dbg(&i2c->adap.dev, "ACK ok, sending (0x%02x)\n",
+ i2c->msg->buf[i2c->msg_idx]);
+ } else if (i2c->is_last) {
+ /* Last message, send stop */
+ writel(LPC24XX_STO | LPC24XX_AA,
+ i2c->reg_base + LPC24XX_I2CONSET);
+ writel(LPC24XX_SI, i2c->reg_base + LPC24XX_I2CONCLR);
+ i2c->msg_status = 0;
+ dev_dbg(&i2c->adap.dev, "ACK ok, sending stop\n");
+ disable_irq_nosync(i2c->irq);
+ } else {
+ i2c->msg_status = 0;
+ dev_dbg(&i2c->adap.dev,
+ "ACK ok, idling until next message start\n");
+ disable_irq_nosync(i2c->irq);
+ }
+
+ i2c->msg_idx++;
+ break;
+
+ case MR_ADDR_R_ACK:
+ /* Receive first byte from slave */
+ if (i2c->msg->len == 1) {
+ /* Last byte, return NACK */
+ writel(LPC24XX_AA, i2c->reg_base + LPC24XX_I2CONCLR);
+ } else {
+ /* Not last byte, return ACK */
+ writel(LPC24XX_AA, i2c->reg_base + LPC24XX_I2CONSET);
+ }
+
+ writel(LPC24XX_STA, i2c->reg_base + LPC24XX_I2CONCLR);
+ break;
+
+ case MR_DATA_R_NACK:
+ /*
+ * The I2C shows NACK status on reads, so we need to accept
+ * the NACK as an ACK here. This should be ok, as the real
+ * BACK would of been caught on the address write.
+ */
+ case MR_DATA_R_ACK:
+ /* Data was received */
+ if (i2c->msg_idx < i2c->msg->len) {
+ i2c->msg->buf[i2c->msg_idx] = readl(i2c->reg_base + LPC24XX_I2DAT);
+ dev_dbg(&i2c->adap.dev, "ACK ok, received (0x%02x)\n",
+ i2c->msg->buf[i2c->msg_idx]);
+ }
+
+ /* If transfer is done, send STOP */
+ if (i2c->msg_idx >= i2c->msg->len - 1 && i2c->is_last) {
+ writel(LPC24XX_STO | LPC24XX_AA, i2c->reg_base + LPC24XX_I2CONSET);
+ writel(LPC24XX_SI, i2c->reg_base + LPC24XX_I2CONCLR);
+ i2c->msg_status = 0;
+ dev_dbg(&i2c->adap.dev, "ACK ok, sending stop\n");
+ }
+
+ /* Message is done */
+ if (i2c->msg_idx >= i2c->msg->len - 1) {
+ i2c->msg_status = 0;
+ dev_dbg(&i2c->adap.dev,
+ "ACK ok, idling until next message start\n");
+ disable_irq_nosync(i2c->irq);
+ }
+
+ /*
+ * One pre-last data input, send NACK to tell the slave that
+ * this is going to be the last data byte to be transferred.
+ */
+ if (i2c->msg_idx >= i2c->msg->len - 2) {
+ /* One byte left to receive - NACK */
+ writel(LPC24XX_AA, i2c->reg_base + LPC24XX_I2CONCLR);
+ } else {
+ /* More than one byte left to receive - ACK */
+ writel(LPC24XX_AA, i2c->reg_base + LPC24XX_I2CONSET);
+ }
+
+ writel(LPC24XX_STA, i2c->reg_base + LPC24XX_I2CONCLR);
+ i2c->msg_idx++;
+ break;
+
+ case MX_ADDR_W_NACK:
+ case MX_DATA_W_NACK:
+ case MR_ADDR_R_NACK:
+ /* NACK processing is done */
+ writel(LPC24XX_STO | LPC24XX_AA, i2c->reg_base + LPC24XX_I2CONSET);
+ i2c->msg_status = -ENODEV;
+ dev_dbg(&i2c->adap.dev, "Device NACKed, error\n");
+ disable_irq_nosync(i2c->irq);
+ break;
+
+ case M_DATA_ARB_LOST:
+ /* Arbitration lost */
+ i2c->msg_status = -EIO;
+ dev_dbg(&i2c->adap.dev, "Arbitration lost, error\n");
+
+ /* Release the I2C bus */
+ writel(LPC24XX_STA | LPC24XX_STO, i2c->reg_base + LPC24XX_I2CONCLR);
+ disable_irq_nosync(i2c->irq);
+ break;
+
+ default:
+ /* Unexpected statuses */
+ i2c->msg_status = -EIO;
+ dev_err(&i2c->adap.dev, "Unexpected status, error (0x%x)\n",
+ status);
+ disable_irq_nosync(i2c->irq);
+ break;
+ }
+
+ /* Exit on failure or all bytes transferred */
+ if (i2c->msg_status != -EBUSY)
+ wake_up(&i2c->wait);
+
+ /*
+ * If `msg_status` is zero, then `lpc2k_process_msg()`
+ * is responsible for clearing the SI flag.
+ */
+ if (i2c->msg_status != 0)
+ writel(LPC24XX_SI, i2c->reg_base + LPC24XX_I2CONCLR);
+}
+
+static int lpc2k_process_msg(struct lpc2k_i2c *i2c, int msgidx)
+{
+ int ret;
+
+ dev_dbg(&i2c->adap.dev, "Processing message %d (len=%d) (flags=%x)\n",
+ msgidx, i2c->msg->len, i2c->msg->flags);
+
+ /* A new transfer is kicked off by initiating a start condition */
+ if (!msgidx) {
+ dev_dbg(&i2c->adap.dev, "Start sent\n");
+ writel(LPC24XX_STA, i2c->reg_base + LPC24XX_I2CONSET);
+ } else {
+ /*
+ * A multi-message I2C transfer continues where the
+ * previous I2C transfer left off and uses the
+ * current condition of the I2C adapter.
+ */
+ if (unlikely(i2c->msg->flags & I2C_M_NOSTART)) {
+ WARN_ON(i2c->msg->len == 0);
+
+ if (!(i2c->msg->flags & I2C_M_RD)) {
+ /* Start transmit of data */
+ writel(i2c->msg->buf[0], i2c->reg_base + LPC24XX_I2DAT);
+ i2c->msg_idx++;
+ dev_dbg(&i2c->adap.dev, "New data sent\n");
+ } else {
+ dev_dbg(&i2c->adap.dev, "New data incoming\n");
+ }
+ } else {
+ /* Start or repeated start */
+ dev_dbg(&i2c->adap.dev, "Repeated start sent\n");
+ writel(LPC24XX_STA, i2c->reg_base + LPC24XX_I2CONSET);
+ }
+
+ writel(LPC24XX_SI, i2c->reg_base + LPC24XX_I2CONCLR);
+ }
+
+ enable_irq(i2c->irq);
+
+ /* Wait for transfer completion */
+ if (wait_event_timeout(i2c->wait, i2c->msg_status != -EBUSY,
+ msecs_to_jiffies(1000)) == 0) {
+ disable_irq_nosync(i2c->irq);
+ dev_dbg(&i2c->adap.dev, "Transfer timed out!\n");
+
+ return -ETIMEDOUT;
+ }
+
+ ret = i2c->msg_status;
+ if (ret == 0)
+ dev_dbg(&i2c->adap.dev, "Transfer successful\n");
+ else
+ dev_dbg(&i2c->adap.dev, "Transfer failed (%d)\n", ret);
+
+ return ret;
+}
+
+static int i2c_lpc2k_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+ int msg_num)
+{
+ struct lpc2k_i2c *i2c = i2c_get_adapdata(adap);
+ int ret, i;
+ u32 stat;
+
+ /* Check for bus idle condition */
+ stat = readl(i2c->reg_base + LPC24XX_I2STAT);
+ if (stat != M_I2C_IDLE) {
+ /* Something is holding the bus, try to clear it */
+ ret = i2c_lpc2k_clear_arb(i2c);
+ if (ret) {
+ dev_warn(&i2c->adap.dev, "Bus is not idle\n");
+ return ret;
+ }
+ }
+
+ dev_dbg(&i2c->adap.dev, "Processing total messages = %d\n", msg_num);
+
+ /* Process a single message at a time */
+ for (i = 0; i < msg_num; i++) {
+ /* Save message pointer and current message data index */
+ i2c->msg = &msgs[i];
+ i2c->msg_idx = 0;
+ i2c->msg_status = -EBUSY;
+ i2c->is_last = (i == (msg_num - 1));
+
+ ret = lpc2k_process_msg(i2c, i);
+ if (ret)
+ return ret;
+ }
+
+ return msg_num;
+}
+
+static irqreturn_t i2c_lpc2k_handler(int irq, void *dev_id)
+{
+ struct lpc2k_i2c *i2c = dev_id;
+
+ if (readl(i2c->reg_base + LPC24XX_I2CONSET) & LPC24XX_SI) {
+ i2c_lpc2k_pump_msg(i2c);
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+static u32 i2c_lpc2k_functionality(struct i2c_adapter *adap)
+{
+ /* Only emulated SMBus for now */
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm i2c_lpc2k_algorithm = {
+ .master_xfer = i2c_lpc2k_xfer,
+ .functionality = i2c_lpc2k_functionality,
+};
+
+static int i2c_lpc2k_probe(struct platform_device *pdev)
+{
+ struct lpc2k_i2c *i2c;
+ struct resource *res;
+ u32 bus_clk_rate;
+ u32 scl_high;
+ u32 clkrate;
+ int ret;
+
+ i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
+ if (!i2c)
+ return -ENOMEM;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ i2c->reg_base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(i2c->reg_base))
+ return PTR_ERR(i2c->reg_base);
+
+ i2c->irq = platform_get_irq(pdev, 0);
+ if (i2c->irq < 0) {
+ dev_err(&pdev->dev, "can't get interrupt resource\n");
+ return i2c->irq;
+ }
+
+ init_waitqueue_head(&i2c->wait);
+
+ i2c->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(i2c->clk)) {
+ dev_err(&pdev->dev, "error getting clock\n");
+ return PTR_ERR(i2c->clk);
+ }
+
+ ret = clk_prepare_enable(i2c->clk);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to enable clock.\n");
+ return ret;
+ }
+
+ ret = devm_request_irq(&pdev->dev, i2c->irq, i2c_lpc2k_handler, 0,
+ dev_name(&pdev->dev), i2c);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "can't request interrupt.\n");
+ goto fail_clk;
+ }
+
+ disable_irq_nosync(i2c->irq);
+
+ /* Place controller is a known state */
+ i2c_lpc2k_reset(i2c);
+
+ ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+ &bus_clk_rate);
+ if (ret)
+ bus_clk_rate = 100000; /* 100 kHz default clock rate */
+
+ clkrate = clk_get_rate(i2c->clk);
+ if (clkrate == 0) {
+ dev_err(&pdev->dev, "can't get I2C base clock\n");
+ ret = -EINVAL;
+ goto fail_clk;
+ }
+
+ /* Setup I2C dividers to generate clock with proper duty cycle */
+ clkrate = clkrate / bus_clk_rate;
+ if (bus_clk_rate <= 100000)
+ scl_high = (clkrate * I2C_STD_MODE_DUTY) / 100;
+ else if (bus_clk_rate <= 400000)
+ scl_high = (clkrate * I2C_FAST_MODE_DUTY) / 100;
+ else
+ scl_high = (clkrate * I2C_FAST_MODE_PLUS_DUTY) / 100;
+
+ writel(scl_high, i2c->reg_base + LPC24XX_I2SCLH);
+ writel(clkrate - scl_high, i2c->reg_base + LPC24XX_I2SCLL);
+
+ platform_set_drvdata(pdev, i2c);
+
+ i2c_set_adapdata(&i2c->adap, i2c);
+ i2c->adap.owner = THIS_MODULE;
+ strlcpy(i2c->adap.name, "LPC2K I2C adapter", sizeof(i2c->adap.name));
+ i2c->adap.algo = &i2c_lpc2k_algorithm;
+ i2c->adap.dev.parent = &pdev->dev;
+ i2c->adap.dev.of_node = pdev->dev.of_node;
+ i2c->adap.nr = pdev->id;
+
+ ret = i2c_add_numbered_adapter(&i2c->adap);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to add bus!\n");
+ goto fail_clk;
+ }
+
+ dev_info(&pdev->dev, "LPC2K I2C adapter\n");
+
+ return 0;
+
+fail_clk:
+ clk_disable_unprepare(i2c->clk);
+ return ret;
+}
+
+static int i2c_lpc2k_remove(struct platform_device *dev)
+{
+ struct lpc2k_i2c *i2c = platform_get_drvdata(dev);
+
+ i2c_del_adapter(&i2c->adap);
+ clk_disable_unprepare(i2c->clk);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM
+static int i2c_lpc2k_suspend(struct device *dev)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct lpc2k_i2c *i2c = platform_get_drvdata(pdev);
+
+ clk_disable(i2c->clk);
+
+ return 0;
+}
+
+static int i2c_lpc2k_resume(struct device *dev)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct lpc2k_i2c *i2c = platform_get_drvdata(pdev);
+
+ clk_enable(i2c->clk);
+ i2c_lpc2k_reset(i2c);
+
+ return 0;
+}
+
+static const struct dev_pm_ops i2c_lpc2k_dev_pm_ops = {
+ .suspend_noirq = i2c_lpc2k_suspend,
+ .resume_noirq = i2c_lpc2k_resume,
+};
+
+#define I2C_LPC2K_DEV_PM_OPS (&i2c_lpc2k_dev_pm_ops)
+#else
+#define I2C_LPC2K_DEV_PM_OPS NULL
+#endif
+
+static const struct of_device_id lpc2k_i2c_match[] = {
+ { .compatible = "nxp,lpc1788-i2c" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, lpc2k_i2c_match);
+
+static struct platform_driver i2c_lpc2k_driver = {
+ .probe = i2c_lpc2k_probe,
+ .remove = i2c_lpc2k_remove,
+ .driver = {
+ .name = "lpc2k-i2c",
+ .pm = I2C_LPC2K_DEV_PM_OPS,
+ .of_match_table = lpc2k_i2c_match,
+ },
+};
+module_platform_driver(i2c_lpc2k_driver);
+
+MODULE_AUTHOR("Kevin Wells <kevin.wells at nxp.com>");
+MODULE_DESCRIPTION("I2C driver for LPC2xxx devices");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:lpc2k-i2c");
--
1.8.0
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