Revision 6e474083f3daf3a3546737f5d7d502ad12eb257c authored by Wei Xu on 01 December 2017, 10:10:36 UTC, committed by David S. Miller on 03 December 2017, 02:31:03 UTC
Matthew found a roughly 40% tcp throughput regression with commit c67df11f(vhost_net: try batch dequing from skb array) as discussed in the following thread: https://www.mail-archive.com/netdev@vger.kernel.org/msg187936.html Eventually we figured out that it was a skb leak in handle_rx() when sending packets to the VM. This usually happens when a guest can not drain out vq as fast as vhost fills in, afterwards it sets off the traffic jam and leaks skb(s) which occurs as no headcount to send on the vq from vhost side. This can be avoided by making sure we have got enough headcount before actually consuming a skb from the batched rx array while transmitting, which is simply done by moving checking the zero headcount a bit ahead. Signed-off-by: Wei Xu <wexu@redhat.com> Reported-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent fa935ca
i2c-cadence.c
/*
* 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>
#include <linux/of.h>
#include <linux/pm_runtime.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)
/* timeout for pm runtime autosuspend */
#define CNDS_I2C_PM_TIMEOUT 1000 /* ms */
#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_TIMEOUT_MAX 0xFF
#define CDNS_I2C_BROKEN_HOLD_BIT BIT(0)
#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
*
* @dev: Pointer to device 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
* @send_count: Number of bytes still expected to send
* @recv_count: Number of bytes still expected to receive
* @curr_recv_count: Number of bytes to be received in current transfer
* @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
* @quirks: flag for broken hold bit usage in r1p10
*/
struct cdns_i2c {
struct device *dev;
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;
unsigned int send_count;
unsigned int recv_count;
unsigned int curr_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;
u32 quirks;
};
struct cdns_platform_data {
u32 quirks;
};
#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);
}
static inline bool cdns_is_holdquirk(struct cdns_i2c *id, bool hold_wrkaround)
{
return (hold_wrkaround &&
(id->curr_recv_count == CDNS_I2C_FIFO_DEPTH + 1));
}
/**
* 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, updatetx;
unsigned int bytes_to_send;
bool hold_quirk;
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);
cdns_i2c_writereg(isr_status, 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;
}
/*
* Check if transfer size register needs to be updated again for a
* large data receive operation.
*/
updatetx = 0;
if (id->recv_count > id->curr_recv_count)
updatetx = 1;
hold_quirk = (id->quirks & CDNS_I2C_BROKEN_HOLD_BIT) && updatetx;
/* When receiving, handle data interrupt and completion interrupt */
if (id->p_recv_buf &&
((isr_status & CDNS_I2C_IXR_COMP) ||
(isr_status & CDNS_I2C_IXR_DATA))) {
/* Read data if receive data valid is set */
while (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) &
CDNS_I2C_SR_RXDV) {
/*
* Clear hold bit that was set for FIFO control if
* RX data left is less than FIFO depth, unless
* repeated start is selected.
*/
if ((id->recv_count < CDNS_I2C_FIFO_DEPTH) &&
!id->bus_hold_flag)
cdns_i2c_clear_bus_hold(id);
*(id->p_recv_buf)++ =
cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET);
id->recv_count--;
id->curr_recv_count--;
if (cdns_is_holdquirk(id, hold_quirk))
break;
}
/*
* The controller sends NACK to the slave when transfer size
* register reaches zero without considering the HOLD bit.
* This workaround is implemented for large data transfers to
* maintain transfer size non-zero while performing a large
* receive operation.
*/
if (cdns_is_holdquirk(id, hold_quirk)) {
/* wait while fifo is full */
while (cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET) !=
(id->curr_recv_count - CDNS_I2C_FIFO_DEPTH))
;
/*
* Check number of bytes to be received against maximum
* transfer size and update register accordingly.
*/
if (((int)(id->recv_count) - CDNS_I2C_FIFO_DEPTH) >
CDNS_I2C_TRANSFER_SIZE) {
cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE,
CDNS_I2C_XFER_SIZE_OFFSET);
id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE +
CDNS_I2C_FIFO_DEPTH;
} else {
cdns_i2c_writereg(id->recv_count -
CDNS_I2C_FIFO_DEPTH,
CDNS_I2C_XFER_SIZE_OFFSET);
id->curr_recv_count = id->recv_count;
}
} else if (id->recv_count && !hold_quirk &&
!id->curr_recv_count) {
/* Set the slave address in address register*/
cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK,
CDNS_I2C_ADDR_OFFSET);
if (id->recv_count > CDNS_I2C_TRANSFER_SIZE) {
cdns_i2c_writereg(CDNS_I2C_TRANSFER_SIZE,
CDNS_I2C_XFER_SIZE_OFFSET);
id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE;
} else {
cdns_i2c_writereg(id->recv_count,
CDNS_I2C_XFER_SIZE_OFFSET);
id->curr_recv_count = id->recv_count;
}
}
/* Clear hold (if not repeated start) and signal completion */
if ((isr_status & CDNS_I2C_IXR_COMP) && !id->recv_count) {
if (!id->bus_hold_flag)
cdns_i2c_clear_bus_hold(id);
done_flag = 1;
}
status = IRQ_HANDLED;
}
/* When sending, handle transfer complete interrupt */
if ((isr_status & CDNS_I2C_IXR_COMP) && !id->p_recv_buf) {
/*
* If there is more data to be sent, calculate the
* space available in FIFO and fill 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);
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;
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;
id->curr_recv_count = id->recv_count;
/*
* 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);
id->curr_recv_count = CDNS_I2C_TRANSFER_SIZE;
} else {
cdns_i2c_writereg(id->recv_count, CDNS_I2C_XFER_SIZE_OFFSET);
}
/* Set the slave address in address register - triggers operation */
cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK,
CDNS_I2C_ADDR_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);
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)
{
unsigned long time_left;
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 */
time_left = wait_for_completion_timeout(&id->xfer_done, adap->timeout);
if (time_left == 0) {
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;
bool hold_quirk;
ret = pm_runtime_get_sync(id->dev);
if (ret < 0)
return ret;
/* Check if the bus is free */
if (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & CDNS_I2C_SR_BA) {
ret = -EAGAIN;
goto out;
}
hold_quirk = !!(id->quirks & CDNS_I2C_BROKEN_HOLD_BIT);
/*
* Set the flag to one when multiple messages are to be
* processed with a repeated start.
*/
if (num > 1) {
/*
* This controller does not give completion interrupt after a
* master receive message if HOLD bit is set (repeated start),
* resulting in SW timeout. Hence, if a receive message is
* followed by any other message, an error is returned
* indicating that this sequence is not supported.
*/
for (count = 0; (count < num - 1 && hold_quirk); count++) {
if (msgs[count].flags & I2C_M_RD) {
dev_warn(adap->dev.parent,
"Can't do repeated start after a receive message\n");
ret = -EOPNOTSUPP;
goto out;
}
}
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)
goto out;
/* Report the other error interrupts to application */
if (id->err_status) {
cdns_i2c_master_reset(adap);
if (id->err_status & CDNS_I2C_IXR_NACK) {
ret = -ENXIO;
goto out;
}
ret = -EIO;
goto out;
}
}
ret = num;
out:
pm_runtime_mark_last_busy(id->dev);
pm_runtime_put_autosuspend(id->dev);
return ret;
}
/**
* 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 acknowledge 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 (pm_runtime_suspended(id->dev))
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_runtime_suspend - Runtime 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_runtime_suspend(struct device *dev)
{
struct cdns_i2c *xi2c = dev_get_drvdata(dev);
clk_disable(xi2c->clk);
return 0;
}
/**
* cdns_i2c_runtime_resume - Runtime resume
* @dev: Address of the platform_device structure
*
* Runtime resume callback.
*
* Return: 0 on success and error value on error
*/
static int __maybe_unused cdns_i2c_runtime_resume(struct device *dev)
{
struct cdns_i2c *xi2c = dev_get_drvdata(dev);
int ret;
ret = clk_enable(xi2c->clk);
if (ret) {
dev_err(dev, "Cannot enable clock.\n");
return ret;
}
return 0;
}
static const struct dev_pm_ops cdns_i2c_dev_pm_ops = {
SET_RUNTIME_PM_OPS(cdns_i2c_runtime_suspend,
cdns_i2c_runtime_resume, NULL)
};
static const struct cdns_platform_data r1p10_i2c_def = {
.quirks = CDNS_I2C_BROKEN_HOLD_BIT,
};
static const struct of_device_id cdns_i2c_of_match[] = {
{ .compatible = "cdns,i2c-r1p10", .data = &r1p10_i2c_def },
{ .compatible = "cdns,i2c-r1p14",},
{ /* end of table */ }
};
MODULE_DEVICE_TABLE(of, cdns_i2c_of_match);
/**
* 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;
const struct of_device_id *match;
id = devm_kzalloc(&pdev->dev, sizeof(*id), GFP_KERNEL);
if (!id)
return -ENOMEM;
id->dev = &pdev->dev;
platform_set_drvdata(pdev, id);
match = of_match_node(cdns_i2c_of_match, pdev->dev.of_node);
if (match && match->data) {
const struct cdns_platform_data *data = match->data;
id->quirks = data->quirks;
}
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.owner = THIS_MODULE;
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");
pm_runtime_enable(id->dev);
pm_runtime_set_autosuspend_delay(id->dev, CNDS_I2C_PM_TIMEOUT);
pm_runtime_use_autosuspend(id->dev);
pm_runtime_set_active(id->dev);
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;
}
/*
* Cadence I2C controller has a bug wherein it generates
* invalid read transaction after HW timeout in master receiver mode.
* HW timeout is not used by this driver and the interrupt is disabled.
* But the feature itself cannot be disabled. Hence maximum value
* is written to this register to reduce the chances of error.
*/
cdns_i2c_writereg(CDNS_I2C_TIMEOUT_MAX, CDNS_I2C_TIME_OUT_OFFSET);
ret = i2c_add_adapter(&id->adap);
if (ret < 0)
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);
pm_runtime_set_suspended(&pdev->dev);
pm_runtime_disable(&pdev->dev);
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);
pm_runtime_disable(&pdev->dev);
return 0;
}
static struct platform_driver cdns_i2c_drv = {
.driver = {
.name = DRIVER_NAME,
.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");
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