diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-cadence.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-cadence.c | 905 |
1 files changed, 905 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c new file mode 100644 index 00000000000..63f3f03ecc9 --- /dev/null +++ b/drivers/i2c/busses/i2c-cadence.c @@ -0,0 +1,905 @@ +/* + * 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 /* IRQ 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 /* IRQ Enable Register, WO */ +#define CDNS_I2C_IDR_OFFSET 0x28 /* IRQ Disable Register, WO */ + +/* Control Register Bit mask definitions */ +#define CDNS_I2C_CR_HOLD BIT(4) /* Hold Bus bit */ +#define CDNS_I2C_CR_ACK_EN BIT(3) +#define CDNS_I2C_CR_NEA BIT(2) +#define CDNS_I2C_CR_MS BIT(1) +/* 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) + +/* + * 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_ARB_LOST BIT(9) +#define CDNS_I2C_IXR_RX_UNF BIT(7) +#define CDNS_I2C_IXR_TX_OVF BIT(6) +#define CDNS_I2C_IXR_RX_OVF BIT(5) +#define CDNS_I2C_IXR_SLV_RDY BIT(4) +#define CDNS_I2C_IXR_TO BIT(3) +#define CDNS_I2C_IXR_NACK BIT(2) +#define CDNS_I2C_IXR_DATA BIT(1) +#define CDNS_I2C_IXR_COMP BIT(0) + +#define CDNS_I2C_IXR_ALL_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \ + CDNS_I2C_IXR_RX_UNF | \ + CDNS_I2C_IXR_TX_OVF | \ + CDNS_I2C_IXR_RX_OVF | \ + CDNS_I2C_IXR_SLV_RDY | \ + CDNS_I2C_IXR_TO | \ + CDNS_I2C_IXR_NACK | \ + CDNS_I2C_IXR_DATA | \ + CDNS_I2C_IXR_COMP) + +#define CDNS_I2C_IXR_ERR_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \ + CDNS_I2C_IXR_RX_UNF | \ + CDNS_I2C_IXR_TX_OVF | \ + CDNS_I2C_IXR_RX_OVF | \ + CDNS_I2C_IXR_NACK) + +#define CDNS_I2C_ENABLED_INTR_MASK (CDNS_I2C_IXR_ARB_LOST | \ + CDNS_I2C_IXR_RX_UNF | \ + CDNS_I2C_IXR_TX_OVF | \ + CDNS_I2C_IXR_RX_OVF | \ + CDNS_I2C_IXR_NACK | \ + CDNS_I2C_IXR_DATA | \ + CDNS_I2C_IXR_COMP) + +#define CDNS_I2C_TIMEOUT msecs_to_jiffies(1000) + +#define CDNS_I2C_FIFO_DEPTH 16 +/* 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 +/* 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_SPEED_DEFAULT 100000 + +#define CDNS_I2C_DIVA_MAX 4 +#define CDNS_I2C_DIVB_MAX 64 + +#define cdns_i2c_readreg(offset) readl_relaxed(id->membase + offset) +#define cdns_i2c_writereg(val, offset) writel_relaxed(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 + * @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; + 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() - Clear 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 + * + * This function handles the data interrupt, transfer complete interrupt and + * the error interrupts of the I2C device. + * + * Return: IRQ_HANDLED always + */ +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; + irqreturn_t status = IRQ_NONE; + + 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; + status = IRQ_HANDLED; + } + + /* 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 -= 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); + + status = IRQ_HANDLED; + } + + /* 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; + } + + status = IRQ_HANDLED; + } + + /* Update the status for errors */ + id->err_status = isr_status & CDNS_I2C_IXR_ERR_INTR_MASK; + if (id->err_status) + status = IRQ_HANDLED; + + cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET); + + if (done_flag) + complete(&id->xfer_done); + + return status; +} + +/** + * 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) + 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_MASK, 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_MASK, 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; + + id->p_msg = msg; + id->err_status = 0; + reinit_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, adap->timeout); + 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) + return -EAGAIN; + + 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 + * + * Initiates the send/recv activity based on the transfer message received. + * + * Return: number of msgs processed on success, negative error otherwise + */ +static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, + int num) +{ + int ret, count; + u32 reg; + struct cdns_i2c *id = adap->algo_data; + + /* Check if the bus is free */ + if (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & CDNS_I2C_SR_BA) + return -EAGAIN; + + /* + * 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 */ + if (id->err_status) { + cdns_i2c_master_reset(adap); + + if (id->err_status & CDNS_I2C_IXR_NACK) + return -ENXIO; + + 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) + * + * 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. + * + * Return: 0 on success, negative errno otherwise. + */ +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 + * + * 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. + * + * Return: 0 on success, negative error otherwise + */ +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 + * + * 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. + * + * Return: NOTIFY_STOP if the rate change should be aborted, NOTIFY_OK + * to acknowedge the change, NOTIFY_DONE if the notification is + * considered irrelevant. + */ +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; + } +} + +/** + * cdns_i2c_suspend - Suspend method for the driver + * @_dev: Address of the platform_device structure + * + * Put the driver into low power mode. + * + * Return: 0 always + */ +static int __maybe_unused 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 + * + * Resume operation after suspend. + * + * Return: 0 on success and error value on error + */ +static int __maybe_unused 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; +} + +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 + * + * 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. + * + * Return: 0 on success, negative error otherwise + */ +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.dev.of_node = pdev->dev.of_node; + id->adap.algo = &cdns_i2c_algo; + id->adap.timeout = CDNS_I2C_TIMEOUT; + id->adap.retries = 3; /* Default retry value. */ + id->adap.algo_data = id; + id->adap.dev.parent = &pdev->dev; + init_completion(&id->xfer_done); + snprintf(id->adap.name, sizeof(id->adap.name), + "Cadence I2C at %08lx", (unsigned long)r_mem->start); + + 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_DEFAULT; + + cdns_i2c_writereg(CDNS_I2C_CR_ACK_EN | CDNS_I2C_CR_NEA | CDNS_I2C_CR_MS, + CDNS_I2C_CR_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_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 + * + * This function frees all the resources allocated to the device. + * + * Return: 0 always + */ +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"); |