I'll send a v2 which will include the changes suggested in this thread: https://lkml.org/lkml/2014/3/11/64 Sören On Tue, 2014-03-04 at 08:42AM -0800, 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@xxxxxxxxxx> > --- > 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 | 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 c6d0e93eff62..fab9e94c3eb2 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..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..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 > > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
