[PATCH v3 1/2] i2c: Add driver for Cadence I2C controller
Sören Brinkmann
soren.brinkmann at xilinx.com
Wed Mar 19 18:03:18 EDT 2014
ping?
Thanks,
Sören
On Tue, 2014-03-11 at 09:50AM -0700, Soren Brinkmann wrote:
> Add a driver for the Cadence I2C controller. This controller is for
> example found in Xilinx Zynq.
>
> Signed-off-by: Soren Brinkmann <soren.brinkmann at xilinx.com>
> ---
> v3:
> - incorporate signal handling changes from Mike Looijmans
> <mike.looijmans at topic.nl> (https://lkml.org/lkml/2014/3/11/64)
> v2:
> - make driver depend on COMMON_CLK instead of ARCH_ZYNQ
> ---
> .../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 | 898 +++++++++++++++++++++
> 5 files changed, 928 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 at 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 1ecfde109667..58b6bb1892d0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -1403,6 +1403,7 @@ 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..6754d2ed04b3 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 COMMON_CLK
> + 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..bcc5eda3337b
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-cadence.c
> @@ -0,0 +1,898 @@
> +/*
> + * 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_timeout(&id->xfer_done, HZ);
> + if (!ret) {
> + cdns_i2c_master_reset(adap);
> + dev_err(id->adap.dev.parent,
> + "timeout waiting on completion\n");
> + return -ETIMEDOUT;
> + }
> +
> + 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
>
>
More information about the linux-arm-kernel
mailing list