[PATCH 1/2] i2c: Add driver for Cadence I2C controller

Soren Brinkmann
2014-03-01T00:00:45Z

Add a driver for the Cadence I2C controller. This controller is for
example found in Xilinx Zynq.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
.../devicetree/bindings/i2c/i2c-cadence.txt | 21 +
MAINTAINERS | 1 +
drivers/i2c/busses/Kconfig | 7 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-cadence.c | 901 +++++++++++++++++++++
5 files changed, 931 insertions(+)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-cadence.txt
create mode 100644 drivers/i2c/busses/i2c-cadence.c

diff --git a/Documentation/devicetree/bindings/i2c/i2c-cadence.txt b/Documentation/devicetree/bindings/i2c/i2c-cadence.txt
new file mode 100644
index 000000000000..685adf513111
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-cadence.txt
@@ -0,0 +1,21 @@
+Binding for the Cadence I2C controller
+
+Required properties:
+ compatible: Compatibility string. Must be 'cdns,i2c-r1p10'.
+ clocks: From common clock bindings. Phandle to input clock.
+
+Optional properties:
+ clock-frequency: Desired operating frequency, in Hz, of the bus (actual may
+ be lower). Defaults to 400000 if not specified.
+
+Example:
+
+ i2c@e0004000 {
+ compatible = "cdns,i2c-r1p10";
+ clocks = <&clkc 38>;
+ interrupts = <0 25 4>;
+ reg = <0xE0004000 0x1000>;
+ clock-frequency = <400000>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index df8869d49c3f..cd1ce0d53ff0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1402,6 +1402,7 @@ F: drivers/cpuidle/cpuidle-zynq.c
N: zynq
N: xilinx
F: drivers/clocksource/cadence_ttc_timer.c
+F: drivers/i2c/busses/i2c-cadence.c
F: drivers/mmc/host/sdhci-of-arasan.c

ARM SMMU DRIVER
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index f5ed03164d86..7806c1654068 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -375,6 +375,13 @@ config I2C_BLACKFIN_TWI_CLK_KHZ
help
The unit of the TWI clock is kHz.

+config I2C_CADENCE
+ tristate "Cadence I2C Controller"
+ depends on ARCH_ZYNQ
+ help
+ Say yes here to select Cadence I2C Host Controller. This controller is
+ e.g. used by Xilinx Zynq.
+
config I2C_CBUS_GPIO
tristate "CBUS I2C driver"
depends on GPIOLIB
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index a08931fe73e1..f9ebb8c6cdc1 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-$(CONFIG_I2C_BCM2835) += i2c-bcm2835.o
obj-$(CONFIG_I2C_BLACKFIN_TWI) += i2c-bfin-twi.o
+obj-$(CONFIG_I2C_CADENCE) += i2c-cadence.o
obj-$(CONFIG_I2C_CBUS_GPIO) += i2c-cbus-gpio.o
obj-$(CONFIG_I2C_CPM) += i2c-cpm.o
obj-$(CONFIG_I2C_DAVINCI) += i2c-davinci.o
diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
new file mode 100644
index 000000000000..5ce1bba6402b
--- /dev/null
+++ b/drivers/i2c/busses/i2c-cadence.c
@@ -0,0 +1,901 @@
+/*
+ * I2C bus driver for the Cadence I2C controller.
+ *
+ * Copyright (C) 2009 - 2014 Xilinx, Inc.
+ *
+ * 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/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+/* Register offsets for the I2C device. */
+#define CDNS_I2C_CR_OFFSET 0x00 /* Control Register, RW */
+#define CDNS_I2C_SR_OFFSET 0x04 /* Status Register, RO */
+#define CDNS_I2C_ADDR_OFFSET 0x08 /* I2C Address Register, RW */
+#define CDNS_I2C_DATA_OFFSET 0x0C /* I2C Data Register, RW */
+#define CDNS_I2C_ISR_OFFSET 0x10 /* Interrupt Status Register, RW */
+#define CDNS_I2C_XFER_SIZE_OFFSET 0x14 /* Transfer Size Register, RW */
+#define CDNS_I2C_TIME_OUT_OFFSET 0x1C /* Time Out Register, RW */
+#define CDNS_I2C_IER_OFFSET 0x24 /* Interrupt Enable Register, WO */
+#define CDNS_I2C_IDR_OFFSET 0x28 /* Interrupt Disable Register, WO */
+
+/* Control Register Bit mask definitions */
+#define CDNS_I2C_CR_HOLD BIT(4) /* Hold Bus bit */
+#define CDNS_I2C_CR_NEA BIT(2)
+/* Read or Write Master transfer 0 = Transmitter, 1 = Receiver */
+#define CDNS_I2C_CR_RW BIT(0)
+/* 1 = Auto init FIFO to zeroes */
+#define CDNS_I2C_CR_CLR_FIFO BIT(6)
+#define CDNS_I2C_CR_DIVA_SHIFT 14
+#define CDNS_I2C_CR_DIVA_MASK (3 << CDNS_I2C_CR_DIVA_SHIFT)
+#define CDNS_I2C_CR_DIVB_SHIFT 8
+#define CDNS_I2C_CR_DIVB_MASK (0x3f << CDNS_I2C_CR_DIVB_SHIFT)
+
+/* Status Register Bit mask definitions */
+#define CDNS_I2C_SR_BA BIT(8)
+#define CDNS_I2C_SR_RXDV BIT(5)
+
+#define CDNS_I2C_TIME_OUT_TO_MASK 0xff
+
+/*
+ * I2C Address Register Bit mask definitions
+ * Normal addressing mode uses [6:0] bits. Extended addressing mode uses [9:0]
+ * bits. A write access to this register always initiates a transfer if the I2C
+ * is in master mode.
+ */
+#define CDNS_I2C_ADDR_MASK 0x000003FF /* I2C Address Mask */
+
+/*
+ * I2C Interrupt Registers Bit mask definitions
+ * All the four interrupt registers (Status/Mask/Enable/Disable) have the same
+ * bit definitions.
+ */
+#define CDNS_I2C_IXR_ALL_INTR_MASK 0x000002FF /* All ISR Mask */
+#define CDNS_I2C_IXR_ERR_INTR_MASK 0x000002EC
+#define CDNS_I2C_IXR_ARB_LOST BIT(9)
+#define CDNS_I2C_IXR_NACK BIT(2)
+#define CDNS_I2C_IXR_DATA BIT(1)
+#define CDNS_I2C_IXR_COMP BIT(0)
+
+#define CDNS_I2C_FIFO_DEPTH 16 /* FIFO Depth */
+#define CDNS_I2C_TIMEOUT (2 * HZ) /* Timeout for bus busy check */
+#define CDNS_I2C_ENABLED_INTR 0x2EF /* Enabled Interrupts */
+
+/* FIFO depth at which the DATA interrupt occurs */
+#define CDNS_I2C_DATA_INTR_DEPTH (CDNS_I2C_FIFO_DEPTH - 2)
+#define CDNS_I2C_MAX_TRANSFER_SIZE 255 /* Max transfer size */
+/* Transfer size in multiples of data interrupt depth */
+#define CDNS_I2C_TRANSFER_SIZE (CDNS_I2C_MAX_TRANSFER_SIZE - 3)
+
+#define DRIVER_NAME "cdns-i2c"
+
+#define CDNS_I2C_SPEED_MAX 400000
+
+#define CDNS_I2C_DIVA_MAX 4
+#define CDNS_I2C_DIVB_MAX 64
+
+#define cdns_i2c_readreg(offset) __raw_readl(id->membase + offset)
+#define cdns_i2c_writereg(val, offset) __raw_writel(val, id->membase + offset)
+
+/**
+ * struct cdns_i2c - I2C device private data structure
+ * @membase: Base address of the I2C device
+ * @adap: I2C adapter instance
+ * @p_msg: Message pointer
+ * @err_status: Error status in Interrupt Status Register
+ * @xfer_done: Transfer complete status
+ * @p_send_buf: Pointer to transmit buffer
+ * @p_recv_buf: Pointer to receive buffer
+ * @suspended: Flag holding the device's PM status
+ * @send_count: Number of bytes still expected to send
+ * @recv_count: Number of bytes still expected to receive
+ * @irq: IRQ number
+ * @cur_timeout: The current timeout value used by the device
+ * @input_clk: Input clock to I2C controller
+ * @i2c_clk: Maximum I2C clock speed
+ * @bus_hold_flag: Flag used in repeated start for clearing HOLD bit
+ * @clk: Pointer to struct clk
+ * @clk_rate_change_nb: Notifier block for clock rate changes
+ */
+struct cdns_i2c {
+ void __iomem *membase;
+ struct i2c_adapter adap;
+ struct i2c_msg *p_msg;
+ int err_status;
+ struct completion xfer_done;
+ unsigned char *p_send_buf;
+ unsigned char *p_recv_buf;
+ u8 suspended;
+ unsigned int send_count;
+ unsigned int recv_count;
+ int irq;
+ int cur_timeout;
+ unsigned long input_clk;
+ unsigned int i2c_clk;
+ unsigned int bus_hold_flag;
+ struct clk *clk;
+ struct notifier_block clk_rate_change_nb;
+};
+
+#define to_cdns_i2c(_nb) container_of(_nb, struct cdns_i2c, \
+ clk_rate_change_nb)
+
+/**
+ * cdns_i2c_clear_bus_hold() - Clar bus hold bit
+ * @id: Pointer to driver data struct
+ *
+ * Helper to clear the controller's bus hold bit.
+ */
+static void cdns_i2c_clear_bus_hold(struct cdns_i2c *id)
+{
+ u32 reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
+ if (reg & CDNS_I2C_CR_HOLD)
+ cdns_i2c_writereg(reg & ~CDNS_I2C_CR_HOLD, CDNS_I2C_CR_OFFSET);
+}
+
+/**
+ * cdns_i2c_isr - Interrupt handler for the I2C device
+ * @irq: irq number for the I2C device
+ * @ptr: void pointer to cdns_i2c structure
+ *
+ * Return: IRQ_HANDLED always
+ *
+ * This function handles the data interrupt, transfer complete interrupt and
+ * the error interrupts of the I2C device.
+ */
+static irqreturn_t cdns_i2c_isr(int irq, void *ptr)
+{
+ unsigned int isr_status, avail_bytes;
+ unsigned int bytes_to_recv, bytes_to_send;
+ struct cdns_i2c *id = ptr;
+ /* Signal completion only after everything is updated */
+ int done_flag = 0;
+
+ isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
+
+ /* Handling nack and arbitration lost interrupt */
+ if (isr_status & (CDNS_I2C_IXR_NACK | CDNS_I2C_IXR_ARB_LOST))
+ done_flag = 1;
+
+ /* Handling Data interrupt */
+ if ((isr_status & CDNS_I2C_IXR_DATA) &&
+ (id->recv_count >= CDNS_I2C_DATA_INTR_DEPTH)) {
+ /* Always read data interrupt threshold bytes */
+ bytes_to_recv = CDNS_I2C_DATA_INTR_DEPTH;
+ id->recv_count = id->recv_count - CDNS_I2C_DATA_INTR_DEPTH;
+ avail_bytes = cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
+
+ /*
+ * if the tranfer size register value is zero, then
+ * check for the remaining bytes and update the
+ * transfer size register.
+ */
+ if (!avail_bytes) {
+ if (id->recv_count > CDNS_I2C_TRANSFER_SIZE)
+ cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE,
+ CDNS_I2C_XFER_SIZE_OFFSET);
+ else
+ cdns_i2c_writereg(id->recv_count,
+ CDNS_I2C_XFER_SIZE_OFFSET);
+ }
+
+ /* Process the data received */
+ while (bytes_to_recv--)
+ *(id->p_recv_buf)++ =
+ cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET);
+
+ if (!id->bus_hold_flag &&
+ (id->recv_count <= CDNS_I2C_FIFO_DEPTH))
+ cdns_i2c_clear_bus_hold(id);
+ }
+
+ /* Handling Transfer Complete interrupt */
+ if (isr_status & CDNS_I2C_IXR_COMP) {
+ if (!id->p_recv_buf) {
+ /*
+ * If the device is sending data If there is further
+ * data to be sent. Calculate the available space
+ * in FIFO and fill the FIFO with that many bytes.
+ */
+ if (id->send_count) {
+ avail_bytes = CDNS_I2C_FIFO_DEPTH -
+ cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
+ if (id->send_count > avail_bytes)
+ bytes_to_send = avail_bytes;
+ else
+ bytes_to_send = id->send_count;
+
+ while (bytes_to_send--) {
+ cdns_i2c_writereg(
+ (*(id->p_send_buf)++),
+ CDNS_I2C_DATA_OFFSET);
+ id->send_count--;
+ }
+ } else {
+ /*
+ * Signal the completion of transaction and
+ * clear the hold bus bit if there are no
+ * further messages to be processed.
+ */
+ done_flag = 1;
+ }
+ if (!id->send_count && !id->bus_hold_flag)
+ cdns_i2c_clear_bus_hold(id);
+ } else {
+ if (!id->bus_hold_flag)
+ cdns_i2c_clear_bus_hold(id);
+ /*
+ * If the device is receiving data, then signal
+ * the completion of transaction and read the data
+ * present in the FIFO. Signal the completion of
+ * transaction.
+ */
+ while (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) &
+ CDNS_I2C_SR_RXDV) {
+ *(id->p_recv_buf)++ =
+ cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET);
+ id->recv_count--;
+ }
+ done_flag = 1;
+ }
+ }
+
+ /* Update the status for errors */
+ id->err_status = isr_status & CDNS_I2C_IXR_ERR_INTR_MASK;
+ cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
+
+ if (done_flag)
+ complete(&id->xfer_done);
+ return IRQ_HANDLED;
+}
+
+/**
+ * cdns_i2c_mrecv - Prepare and start a master receive operation
+ * @id: pointer to the i2c device structure
+ */
+static void cdns_i2c_mrecv(struct cdns_i2c *id)
+{
+ unsigned int ctrl_reg;
+ unsigned int isr_status;
+
+ id->p_recv_buf = id->p_msg->buf;
+ id->recv_count = id->p_msg->len;
+
+ /* Put the controller in master receive mode and clear the FIFO */
+ ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
+ ctrl_reg |= CDNS_I2C_CR_RW | CDNS_I2C_CR_CLR_FIFO;
+
+ if ((id->p_msg->flags & I2C_M_RECV_LEN) == I2C_M_RECV_LEN)
+ id->recv_count = I2C_SMBUS_BLOCK_MAX + 1;
+
+ /*
+ * Check for the message size against FIFO depth and set the
+ * 'hold bus' bit if it is greater than FIFO depth.
+ */
+ if (id->recv_count > CDNS_I2C_FIFO_DEPTH)
+ ctrl_reg |= CDNS_I2C_CR_HOLD;
+
+ cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
+
+ /* Clear the interrupts in interrupt status register */
+ isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
+ cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
+
+ /*
+ * The no. of bytes to receive is checked against the limit of
+ * max transfer size. Set transfer size register with no of bytes
+ * receive if it is less than transfer size and transfer size if
+ * it is more. Enable the interrupts.
+ */
+ if (id->recv_count > CDNS_I2C_TRANSFER_SIZE)
+ cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE,
+ CDNS_I2C_XFER_SIZE_OFFSET);
+ else
+ cdns_i2c_writereg(id->recv_count, CDNS_I2C_XFER_SIZE_OFFSET);
+ /* Clear the bus hold flag if bytes to receive is less than FIFO size */
+ if (!id->bus_hold_flag &&
+ ((id->p_msg->flags & I2C_M_RECV_LEN) != I2C_M_RECV_LEN) &&
+ (id->recv_count <= CDNS_I2C_FIFO_DEPTH))
+ cdns_i2c_clear_bus_hold(id);
+ /* Set the slave address in address register - triggers operation */
+ cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK,
+ CDNS_I2C_ADDR_OFFSET);
+ cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR, CDNS_I2C_IER_OFFSET);
+}
+
+/**
+ * cdns_i2c_msend - Prepare and start a master send operation
+ * @id: pointer to the i2c device
+ */
+static void cdns_i2c_msend(struct cdns_i2c *id)
+{
+ unsigned int avail_bytes;
+ unsigned int bytes_to_send;
+ unsigned int ctrl_reg;
+ unsigned int isr_status;
+
+ id->p_recv_buf = NULL;
+ id->p_send_buf = id->p_msg->buf;
+ id->send_count = id->p_msg->len;
+
+ /* Set the controller in Master transmit mode and clear the FIFO. */
+ ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
+ ctrl_reg &= ~CDNS_I2C_CR_RW;
+ ctrl_reg |= CDNS_I2C_CR_CLR_FIFO;
+
+ /*
+ * Check for the message size against FIFO depth and set the
+ * 'hold bus' bit if it is greater than FIFO depth.
+ */
+ if (id->send_count > CDNS_I2C_FIFO_DEPTH)
+ ctrl_reg |= CDNS_I2C_CR_HOLD;
+ cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
+
+ /* Clear the interrupts in interrupt status register. */
+ isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
+ cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
+
+ /*
+ * Calculate the space available in FIFO. Check the message length
+ * against the space available, and fill the FIFO accordingly.
+ * Enable the interrupts.
+ */
+ avail_bytes = CDNS_I2C_FIFO_DEPTH -
+ cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
+
+ if (id->send_count > avail_bytes)
+ bytes_to_send = avail_bytes;
+ else
+ bytes_to_send = id->send_count;
+
+ while (bytes_to_send--) {
+ cdns_i2c_writereg((*(id->p_send_buf)++), CDNS_I2C_DATA_OFFSET);
+ id->send_count--;
+ }
+
+ /*
+ * Clear the bus hold flag if there is no more data
+ * and if it is the last message.
+ */
+ if (!id->bus_hold_flag && !id->send_count)
+ cdns_i2c_clear_bus_hold(id);
+ /* Set the slave address in address register - triggers operation. */
+ cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK,
+ CDNS_I2C_ADDR_OFFSET);
+
+ cdns_i2c_writereg(CDNS_I2C_ENABLED_INTR, CDNS_I2C_IER_OFFSET);
+}
+
+/**
+ * cdns_i2c_master_reset - Reset the interface
+ * @adap: pointer to the i2c adapter driver instance
+ *
+ * This function cleanup the fifos, clear the hold bit and status
+ * and disable the interrupts.
+ */
+static void cdns_i2c_master_reset(struct i2c_adapter *adap)
+{
+ struct cdns_i2c *id = adap->algo_data;
+ u32 regval;
+
+ /* Disable the interrupts */
+ cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK, CDNS_I2C_IDR_OFFSET);
+ /* Clear the hold bit and fifos */
+ regval = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
+ regval &= ~CDNS_I2C_CR_HOLD;
+ regval |= CDNS_I2C_CR_CLR_FIFO;
+ cdns_i2c_writereg(regval, CDNS_I2C_CR_OFFSET);
+ /* Update the transfercount register to zero */
+ cdns_i2c_writereg(0, CDNS_I2C_XFER_SIZE_OFFSET);
+ /* Clear the interupt status register */
+ regval = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
+ cdns_i2c_writereg(regval, CDNS_I2C_ISR_OFFSET);
+ /* Clear the status register */
+ regval = cdns_i2c_readreg(CDNS_I2C_SR_OFFSET);
+ cdns_i2c_writereg(regval, CDNS_I2C_SR_OFFSET);
+}
+
+static int cdns_i2c_process_msg(struct cdns_i2c *id, struct i2c_msg *msg,
+ struct i2c_adapter *adap)
+{
+ int ret;
+ u32 reg;
+ bool retry = false;
+ unsigned retries = adap->retries;
+
+ id->p_msg = msg;
+ do {
+ id->err_status = 0;
+ init_completion(&id->xfer_done);
+
+ /* Check for the TEN Bit mode on each msg */
+ reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
+ if (msg->flags & I2C_M_TEN) {
+ if (reg & CDNS_I2C_CR_NEA)
+ cdns_i2c_writereg(reg & ~CDNS_I2C_CR_NEA,
+ CDNS_I2C_CR_OFFSET);
+ } else {
+ if (!(reg & CDNS_I2C_CR_NEA))
+ cdns_i2c_writereg(reg | CDNS_I2C_CR_NEA,
+ CDNS_I2C_CR_OFFSET);
+ }
+
+ /* Check for the R/W flag on each msg */
+ if (msg->flags & I2C_M_RD)
+ cdns_i2c_mrecv(id);
+ else
+ cdns_i2c_msend(id);
+
+ /* Wait for the signal of completion */
+ ret = wait_for_completion_interruptible_timeout(
+ &id->xfer_done, HZ);
+ if (ret < 1) {
+ cdns_i2c_master_reset(adap);
+ if (!ret) {
+ dev_err(id->adap.dev.parent,
+ "timeout waiting on completion\n");
+ return -ETIMEDOUT;
+ }
+ return ret;
+ }
+ cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK,
+ CDNS_I2C_IDR_OFFSET);
+
+ /* If it is bus arbitration error, try again */
+ if (id->err_status & CDNS_I2C_IXR_ARB_LOST) {
+ dev_dbg(id->adap.dev.parent,
+ "Lost ownership on bus, trying again\n");
+ if (retries--) {
+ mdelay(2);
+ retry = true;
+ } else {
+ dev_err(id->adap.dev.parent,
+ "Retries completed, exit\n");
+ return -EREMOTEIO;
+ }
+ }
+ } while (retry);
+
+ return 0;
+}
+
+/**
+ * cdns_i2c_master_xfer - The main i2c transfer function
+ * @adap: pointer to the i2c adapter driver instance
+ * @msgs: pointer to the i2c message structure
+ * @num: the number of messages to transfer
+ *
+ * Return: number of msgs processed on success, negative error otherwise
+ *
+ * This function waits for the bus idle condition and updates the timeout if
+ * modified by user. Then initiates the send/recv activity based on the
+ * transfer message received.
+ */
+static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+ int num)
+{
+ struct cdns_i2c *id = adap->algo_data;
+ unsigned long timeout;
+ int ret, count;
+ u32 reg;
+
+ /* Waiting for bus-ready. If bus not ready, it returns after timeout */
+ timeout = jiffies + CDNS_I2C_TIMEOUT;
+ while (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & CDNS_I2C_SR_BA) {
+ if (time_after(jiffies, timeout)) {
+ dev_warn(id->adap.dev.parent,
+ "timedout waiting for bus ready\n");
+ cdns_i2c_master_reset(adap);
+ return -ETIMEDOUT;
+ }
+ schedule_timeout(1);
+ }
+
+ /* The bus is free. Set the new timeout value if updated */
+ if (id->adap.timeout != id->cur_timeout) {
+ cdns_i2c_writereg(id->adap.timeout & CDNS_I2C_TIME_OUT_TO_MASK,
+ CDNS_I2C_TIME_OUT_OFFSET);
+ id->cur_timeout = id->adap.timeout;
+ }
+
+ /*
+ * Set the flag to one when multiple messages are to be
+ * processed with a repeated start.
+ */
+ if (num > 1) {
+ id->bus_hold_flag = 1;
+ reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
+ reg |= CDNS_I2C_CR_HOLD;
+ cdns_i2c_writereg(reg, CDNS_I2C_CR_OFFSET);
+ } else {
+ id->bus_hold_flag = 0;
+ }
+
+ /* Process the msg one by one */
+ for (count = 0; count < num; count++, msgs++) {
+ if (count == (num - 1))
+ id->bus_hold_flag = 0;
+
+ ret = cdns_i2c_process_msg(id, msgs, adap);
+ if (ret)
+ return ret;
+
+ /* Report the other error interrupts to application as EIO */
+ if (id->err_status & 0xE4) {
+ cdns_i2c_master_reset(adap);
+ return -EIO;
+ }
+ }
+
+ return num;
+}
+
+/**
+ * cdns_i2c_func - Returns the supported features of the I2C driver
+ * @adap: pointer to the i2c adapter structure
+ *
+ * Return: 32 bit value, each bit corresponding to a feature
+ */
+static u32 cdns_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
+ (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
+ I2C_FUNC_SMBUS_BLOCK_DATA;
+}
+
+static const struct i2c_algorithm cdns_i2c_algo = {
+ .master_xfer = cdns_i2c_master_xfer,
+ .functionality = cdns_i2c_func,
+};
+
+/**
+ * cdns_i2c_calc_divs - Calculate clock dividers
+ * @f: I2C clock frequency
+ * @input_clk: Input clock frequency
+ * @a: First divider (return value)
+ * @b: Second divider (return value)
+ *
+ * Return: 0 on success, negative errno otherwise.
+ *
+ * f is used as input and output variable. As input it is used as target I2C
+ * frequency. On function exit f holds the actually resulting I2C frequency.
+ */
+static int cdns_i2c_calc_divs(unsigned long *f, unsigned long input_clk,
+ unsigned int *a, unsigned int *b)
+{
+ unsigned long fscl = *f, best_fscl = *f, actual_fscl, temp;
+ unsigned int div_a, div_b, calc_div_a = 0, calc_div_b = 0;
+ unsigned int last_error, current_error;
+
+ /* calculate (divisor_a+1) x (divisor_b+1) */
+ temp = input_clk / (22 * fscl);
+
+ /*
+ * If the calculated value is negative or 0, the fscl input is out of
+ * range. Return error.
+ */
+ if (!temp || (temp > (CDNS_I2C_DIVA_MAX * CDNS_I2C_DIVB_MAX)))
+ return -EINVAL;
+
+ last_error = -1;
+ for (div_a = 0; div_a < CDNS_I2C_DIVA_MAX; div_a++) {
+ div_b = DIV_ROUND_UP(input_clk, 22 * fscl * (div_a + 1));
+
+ if ((div_b < 1) || (div_b > CDNS_I2C_DIVB_MAX))
+ continue;
+ div_b--;
+
+ actual_fscl = input_clk / (22 * (div_a + 1) * (div_b + 1));
+
+ if (actual_fscl > fscl)
+ continue;
+
+ current_error = ((actual_fscl > fscl) ? (actual_fscl - fscl) :
+ (fscl - actual_fscl));
+
+ if (last_error > current_error) {
+ calc_div_a = div_a;
+ calc_div_b = div_b;
+ best_fscl = actual_fscl;
+ last_error = current_error;
+ }
+ }
+
+ *a = calc_div_a;
+ *b = calc_div_b;
+ *f = best_fscl;
+
+ return 0;
+}
+
+/**
+ * cdns_i2c_setclk - This function sets the serial clock rate for the I2C device
+ * @clk_in: I2C clock input frequency in Hz
+ * @id: Pointer to the I2C device structure
+ *
+ * Return: 0 on success, negative error otherwise
+ *
+ * The device must be idle rather than busy transferring data before setting
+ * these device options.
+ * The data rate is set by values in the control register.
+ * The formula for determining the correct register values is
+ * Fscl = Fpclk/(22 x (divisor_a+1) x (divisor_b+1))
+ * See the hardware data sheet for a full explanation of setting the serial
+ * clock rate. The clock can not be faster than the input clock divide by 22.
+ * The two most common clock rates are 100KHz and 400KHz.
+ */
+static int cdns_i2c_setclk(unsigned long clk_in, struct cdns_i2c *id)
+{
+ unsigned int div_a, div_b;
+ unsigned int ctrl_reg;
+ int ret = 0;
+ unsigned long fscl = id->i2c_clk;
+
+ ret = cdns_i2c_calc_divs(&fscl, clk_in, &div_a, &div_b);
+ if (ret)
+ return ret;
+
+ ctrl_reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET);
+ ctrl_reg &= ~(CDNS_I2C_CR_DIVA_MASK | CDNS_I2C_CR_DIVB_MASK);
+ ctrl_reg |= ((div_a << CDNS_I2C_CR_DIVA_SHIFT) |
+ (div_b << CDNS_I2C_CR_DIVB_SHIFT));
+ cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
+
+ return 0;
+}
+
+/**
+ * cdns_i2c_clk_notifier_cb - Clock rate change callback
+ * @nb: Pointer to notifier block
+ * @event: Notification reason
+ * @data: Pointer to notification data object
+ * Return: NOTIFY_STOP if the rate change should be aborted, NOTIFY_OK
+ * to acknowedge the change, NOTIFY_DONE if the notification is
+ * considered irrelevant.
+ *
+ * This function is called when the cdns_i2c input clock frequency changes.
+ * The callback checks whether a valid bus frequency can be generated after the
+ * change. If so, the change is acknowledged, otherwise the change is aborted.
+ * New dividers are written to the HW in the pre- or post change notification
+ * depending on the scaling direction.
+ */
+static int cdns_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long
+ event, void *data)
+{
+ struct clk_notifier_data *ndata = data;
+ struct cdns_i2c *id = to_cdns_i2c(nb);
+
+ if (id->suspended)
+ return NOTIFY_OK;
+
+ switch (event) {
+ case PRE_RATE_CHANGE:
+ {
+ unsigned long input_clk = ndata->new_rate;
+ unsigned long fscl = id->i2c_clk;
+ unsigned int div_a, div_b;
+ int ret;
+
+ ret = cdns_i2c_calc_divs(&fscl, input_clk, &div_a, &div_b);
+ if (ret) {
+ dev_warn(id->adap.dev.parent,
+ "clock rate change rejected\n");
+ return NOTIFY_STOP;
+ }
+
+ /* scale up */
+ if (ndata->new_rate > ndata->old_rate)
+ cdns_i2c_setclk(ndata->new_rate, id);
+
+ return NOTIFY_OK;
+ }
+ case POST_RATE_CHANGE:
+ id->input_clk = ndata->new_rate;
+ /* scale down */
+ if (ndata->new_rate < ndata->old_rate)
+ cdns_i2c_setclk(ndata->new_rate, id);
+ return NOTIFY_OK;
+ case ABORT_RATE_CHANGE:
+ /* scale up */
+ if (ndata->new_rate > ndata->old_rate)
+ cdns_i2c_setclk(ndata->old_rate, id);
+ return NOTIFY_OK;
+ default:
+ return NOTIFY_DONE;
+ }
+}
+
+#ifdef CONFIG_PM_SLEEP
+/**
+ * cdns_i2c_suspend - Suspend method for the driver
+ * @_dev: Address of the platform_device structure
+ * Return: 0 always
+ *
+ * Put the driver into low power mode.
+ */
+static int cdns_i2c_suspend(struct device *_dev)
+{
+ struct platform_device *pdev = container_of(_dev,
+ struct platform_device, dev);
+ struct cdns_i2c *xi2c = platform_get_drvdata(pdev);
+
+ clk_disable(xi2c->clk);
+ xi2c->suspended = 1;
+
+ return 0;
+}
+
+/**
+ * cdns_i2c_resume - Resume from suspend
+ * @_dev: Address of the platform_device structure
+ * Return: 0 on success and error value on error
+ *
+ * Resume operation after suspend.
+ */
+static int cdns_i2c_resume(struct device *_dev)
+{
+ struct platform_device *pdev = container_of(_dev,
+ struct platform_device, dev);
+ struct cdns_i2c *xi2c = platform_get_drvdata(pdev);
+ int ret;
+
+ ret = clk_enable(xi2c->clk);
+ if (ret) {
+ dev_err(_dev, "Cannot enable clock.\n");
+ return ret;
+ }
+
+ xi2c->suspended = 0;
+
+ return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(cdns_i2c_dev_pm_ops, cdns_i2c_suspend,
+ cdns_i2c_resume);
+
+/**
+ * cdns_i2c_probe - Platform registration call
+ * @pdev: Handle to the platform device structure
+ *
+ * Return: 0 on success, negative error otherwise
+ *
+ * This function does all the memory allocation and registration for the i2c
+ * device. User can modify the address mode to 10 bit address mode using the
+ * ioctl call with option I2C_TENBIT.
+ */
+static int cdns_i2c_probe(struct platform_device *pdev)
+{
+ struct resource *r_mem;
+ struct cdns_i2c *id;
+ int ret;
+
+ id = devm_kzalloc(&pdev->dev, sizeof(*id), GFP_KERNEL);
+ if (!id)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, id);
+
+ r_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ id->membase = devm_ioremap_resource(&pdev->dev, r_mem);
+ if (IS_ERR(id->membase))
+ return PTR_ERR(id->membase);
+
+ id->irq = platform_get_irq(pdev, 0);
+
+ id->adap.nr = pdev->id;
+ id->adap.dev.of_node = pdev->dev.of_node;
+ id->adap.algo = &cdns_i2c_algo;
+ id->adap.timeout = 0x1F; /* Default timeout value */
+ id->adap.retries = 3; /* Default retry value. */
+ id->adap.algo_data = id;
+ id->adap.dev.parent = &pdev->dev;
+ snprintf(id->adap.name, sizeof(id->adap.name),
+ "Cadence I2C at %08lx", (unsigned long)r_mem->start);
+
+ id->cur_timeout = id->adap.timeout;
+ id->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(id->clk)) {
+ dev_err(&pdev->dev, "input clock not found.\n");
+ return PTR_ERR(id->clk);
+ }
+ ret = clk_prepare_enable(id->clk);
+ if (ret) {
+ dev_err(&pdev->dev, "Unable to enable clock.\n");
+ return ret;
+ }
+ id->clk_rate_change_nb.notifier_call = cdns_i2c_clk_notifier_cb;
+ if (clk_notifier_register(id->clk, &id->clk_rate_change_nb))
+ dev_warn(&pdev->dev, "Unable to register clock notifier.\n");
+ id->input_clk = clk_get_rate(id->clk);
+
+ ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+ &id->i2c_clk);
+ if (ret || (id->i2c_clk > CDNS_I2C_SPEED_MAX))
+ id->i2c_clk = CDNS_I2C_SPEED_MAX;
+
+ cdns_i2c_writereg(0xE, CDNS_I2C_CR_OFFSET);
+ cdns_i2c_writereg(id->adap.timeout, CDNS_I2C_TIME_OUT_OFFSET);
+
+ ret = cdns_i2c_setclk(id->input_clk, id);
+ if (ret) {
+ dev_err(&pdev->dev, "invalid SCL clock: %u Hz\n", id->i2c_clk);
+ ret = -EINVAL;
+ goto err_clk_dis;
+ }
+
+ ret = devm_request_irq(&pdev->dev, id->irq, cdns_i2c_isr, 0,
+ DRIVER_NAME, id);
+ if (ret) {
+ dev_err(&pdev->dev, "cannot get irq %d\n", id->irq);
+ goto err_clk_dis;
+ }
+
+ ret = i2c_add_numbered_adapter(&id->adap);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "reg adap failed: %d\n", ret);
+ goto err_clk_dis;
+ }
+
+ dev_info(&pdev->dev, "%u kHz mmio %08lx irq %d\n",
+ id->i2c_clk / 1000, (unsigned long)r_mem->start, id->irq);
+
+ return 0;
+
+err_clk_dis:
+ clk_disable_unprepare(id->clk);
+ return ret;
+}
+
+/**
+ * cdns_i2c_remove - Unregister the device after releasing the resources
+ * @pdev: Handle to the platform device structure
+ *
+ * Return: 0 always
+ *
+ * This function frees all the resources allocated to the device.
+ */
+static int cdns_i2c_remove(struct platform_device *pdev)
+{
+ struct cdns_i2c *id = platform_get_drvdata(pdev);
+
+ i2c_del_adapter(&id->adap);
+ clk_notifier_unregister(id->clk, &id->clk_rate_change_nb);
+ clk_disable_unprepare(id->clk);
+
+ return 0;
+}
+
+static const struct of_device_id cdns_i2c_of_match[] = {
+ { .compatible = "cdns,i2c-r1p10", },
+ { /* end of table */}
+};
+MODULE_DEVICE_TABLE(of, cdns_i2c_of_match);
+
+static struct platform_driver cdns_i2c_drv = {
+ .driver = {
+ .name = DRIVER_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = cdns_i2c_of_match,
+ .pm = &cdns_i2c_dev_pm_ops,
+ },
+ .probe = cdns_i2c_probe,
+ .remove = cdns_i2c_remove,
+};
+
+module_platform_driver(cdns_i2c_drv);
+
+MODULE_AUTHOR("Xilinx Inc.");
+MODULE_DESCRIPTION("Cadence I2C bus driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRIVER_NAME);
--
1.9.0.1.g4196000