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linux_dsm_epyc7002/drivers/i2c/busses/i2c-octeon.c
Peter Swain 1bb1ff3e7c i2c: octeon: Improve performance if interrupt is early 
There is a race between the TWSI interrupt and the condition
that is required before proceeding:

Low-level: interrupt flag bit must be set
High-level controller: valid bit must be clear

If the interrupt comes too early and the condition is not met
the wait will time out, and the transfer is aborted leading
to very poor performance.

To avoid this race retry for the condition ~80 µs later.
The retry is avoided on the very first invocation of
wait_event_timeout() (which tests the condition before entering
the wait and is therefore always wrong in this case).

EEPROM reads on 100kHz i2c now measure ~5.2kB/s, about 1/2 what's
achievable, and much better than the worst-case 100 bytes/sec before.

While at it remove the debug print from the low-level wait function.

Signed-off-by: Peter Swain <pswain@cavium.com>
Signed-off-by: Jan Glauber <jglauber@cavium.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2016-04-26 23:19:40 +02:00

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/*
* (C) Copyright 2009-2010
* Nokia Siemens Networks, michael.lawnick.ext@nsn.com
*
* Portions Copyright (C) 2010 - 2016 Cavium, Inc.
*
* This is a driver for the i2c adapter in Cavium Networks' OCTEON processors.
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/atomic.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/io.h>
#include <linux/of.h>
#include <asm/octeon/octeon.h>
#define DRV_NAME "i2c-octeon"
/* Register offsets */
#define SW_TWSI 0x00
#define TWSI_INT 0x10
#define SW_TWSI_EXT 0x18
/* Controller command patterns */
#define SW_TWSI_V BIT_ULL(63) /* Valid bit */
#define SW_TWSI_EIA BIT_ULL(61) /* Extended internal address */
#define SW_TWSI_R BIT_ULL(56) /* Result or read bit */
#define SW_TWSI_SOVR BIT_ULL(55) /* Size override */
#define SW_TWSI_SIZE_SHIFT 52
#define SW_TWSI_ADDR_SHIFT 40
#define SW_TWSI_IA_SHIFT 32 /* Internal address */
/* Controller opcode word (bits 60:57) */
#define SW_TWSI_OP_SHIFT 57
#define SW_TWSI_OP_7 (0ULL << SW_TWSI_OP_SHIFT)
#define SW_TWSI_OP_7_IA (1ULL << SW_TWSI_OP_SHIFT)
#define SW_TWSI_OP_10 (2ULL << SW_TWSI_OP_SHIFT)
#define SW_TWSI_OP_10_IA (3ULL << SW_TWSI_OP_SHIFT)
#define SW_TWSI_OP_TWSI_CLK (4ULL << SW_TWSI_OP_SHIFT)
#define SW_TWSI_OP_EOP (6ULL << SW_TWSI_OP_SHIFT) /* Extended opcode */
/* Controller extended opcode word (bits 34:32) */
#define SW_TWSI_EOP_SHIFT 32
#define SW_TWSI_EOP_TWSI_DATA (SW_TWSI_OP_EOP | 1ULL << SW_TWSI_EOP_SHIFT)
#define SW_TWSI_EOP_TWSI_CTL (SW_TWSI_OP_EOP | 2ULL << SW_TWSI_EOP_SHIFT)
#define SW_TWSI_EOP_TWSI_CLKCTL (SW_TWSI_OP_EOP | 3ULL << SW_TWSI_EOP_SHIFT)
#define SW_TWSI_EOP_TWSI_STAT (SW_TWSI_OP_EOP | 3ULL << SW_TWSI_EOP_SHIFT)
#define SW_TWSI_EOP_TWSI_RST (SW_TWSI_OP_EOP | 7ULL << SW_TWSI_EOP_SHIFT)
/* Controller command and status bits */
#define TWSI_CTL_CE 0x80 /* High level controller enable */
#define TWSI_CTL_ENAB 0x40 /* Bus enable */
#define TWSI_CTL_STA 0x20 /* Master-mode start, HW clears when done */
#define TWSI_CTL_STP 0x10 /* Master-mode stop, HW clears when done */
#define TWSI_CTL_IFLG 0x08 /* HW event, SW writes 0 to ACK */
#define TWSI_CTL_AAK 0x04 /* Assert ACK */
/* Status values */
#define STAT_ERROR 0x00
#define STAT_START 0x08
#define STAT_REP_START 0x10
#define STAT_TXADDR_ACK 0x18
#define STAT_TXADDR_NAK 0x20
#define STAT_TXDATA_ACK 0x28
#define STAT_TXDATA_NAK 0x30
#define STAT_LOST_ARB_38 0x38
#define STAT_RXADDR_ACK 0x40
#define STAT_RXADDR_NAK 0x48
#define STAT_RXDATA_ACK 0x50
#define STAT_RXDATA_NAK 0x58
#define STAT_SLAVE_60 0x60
#define STAT_LOST_ARB_68 0x68
#define STAT_SLAVE_70 0x70
#define STAT_LOST_ARB_78 0x78
#define STAT_SLAVE_80 0x80
#define STAT_SLAVE_88 0x88
#define STAT_GENDATA_ACK 0x90
#define STAT_GENDATA_NAK 0x98
#define STAT_SLAVE_A0 0xA0
#define STAT_SLAVE_A8 0xA8
#define STAT_LOST_ARB_B0 0xB0
#define STAT_SLAVE_LOST 0xB8
#define STAT_SLAVE_NAK 0xC0
#define STAT_SLAVE_ACK 0xC8
#define STAT_AD2W_ACK 0xD0
#define STAT_AD2W_NAK 0xD8
#define STAT_IDLE 0xF8
/* TWSI_INT values */
#define TWSI_INT_ST_INT BIT_ULL(0)
#define TWSI_INT_TS_INT BIT_ULL(1)
#define TWSI_INT_CORE_INT BIT_ULL(2)
#define TWSI_INT_ST_EN BIT_ULL(4)
#define TWSI_INT_TS_EN BIT_ULL(5)
#define TWSI_INT_CORE_EN BIT_ULL(6)
#define TWSI_INT_SDA_OVR BIT_ULL(8)
#define TWSI_INT_SCL_OVR BIT_ULL(9)
#define TWSI_INT_SDA BIT_ULL(10)
#define TWSI_INT_SCL BIT_ULL(11)
#define I2C_OCTEON_EVENT_WAIT 80 /* microseconds */
struct octeon_i2c {
wait_queue_head_t queue;
struct i2c_adapter adap;
int irq;
int hlc_irq; /* For cn7890 only */
u32 twsi_freq;
int sys_freq;
void __iomem *twsi_base;
struct device *dev;
bool hlc_enabled;
void (*int_enable)(struct octeon_i2c *);
void (*int_disable)(struct octeon_i2c *);
void (*hlc_int_enable)(struct octeon_i2c *);
void (*hlc_int_disable)(struct octeon_i2c *);
atomic_t int_enable_cnt;
atomic_t hlc_int_enable_cnt;
};
static void octeon_i2c_writeq_flush(u64 val, void __iomem *addr)
{
__raw_writeq(val, addr);
__raw_readq(addr); /* wait for write to land */
}
/**
* octeon_i2c_reg_write - write an I2C core register
* @i2c: The struct octeon_i2c
* @eop_reg: Register selector
* @data: Value to be written
*
* The I2C core registers are accessed indirectly via the SW_TWSI CSR.
*/
static void octeon_i2c_reg_write(struct octeon_i2c *i2c, u64 eop_reg, u8 data)
{
u64 tmp;
__raw_writeq(SW_TWSI_V | eop_reg | data, i2c->twsi_base + SW_TWSI);
do {
tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
} while ((tmp & SW_TWSI_V) != 0);
}
#define octeon_i2c_ctl_write(i2c, val) \
octeon_i2c_reg_write(i2c, SW_TWSI_EOP_TWSI_CTL, val)
#define octeon_i2c_data_write(i2c, val) \
octeon_i2c_reg_write(i2c, SW_TWSI_EOP_TWSI_DATA, val)
/**
* octeon_i2c_reg_read - read lower bits of an I2C core register
* @i2c: The struct octeon_i2c
* @eop_reg: Register selector
*
* Returns the data.
*
* The I2C core registers are accessed indirectly via the SW_TWSI CSR.
*/
static u8 octeon_i2c_reg_read(struct octeon_i2c *i2c, u64 eop_reg)
{
u64 tmp;
__raw_writeq(SW_TWSI_V | eop_reg | SW_TWSI_R, i2c->twsi_base + SW_TWSI);
do {
tmp = __raw_readq(i2c->twsi_base + SW_TWSI);
} while ((tmp & SW_TWSI_V) != 0);
return tmp & 0xFF;
}
#define octeon_i2c_ctl_read(i2c) \
octeon_i2c_reg_read(i2c, SW_TWSI_EOP_TWSI_CTL)
#define octeon_i2c_data_read(i2c) \
octeon_i2c_reg_read(i2c, SW_TWSI_EOP_TWSI_DATA)
#define octeon_i2c_stat_read(i2c) \
octeon_i2c_reg_read(i2c, SW_TWSI_EOP_TWSI_STAT)
/**
* octeon_i2c_read_int - read the TWSI_INT register
* @i2c: The struct octeon_i2c
*
* Returns the value of the register.
*/
static u64 octeon_i2c_read_int(struct octeon_i2c *i2c)
{
return __raw_readq(i2c->twsi_base + TWSI_INT);
}
/**
* octeon_i2c_write_int - write the TWSI_INT register
* @i2c: The struct octeon_i2c
* @data: Value to be written
*/
static void octeon_i2c_write_int(struct octeon_i2c *i2c, u64 data)
{
octeon_i2c_writeq_flush(data, i2c->twsi_base + TWSI_INT);
}
/**
* octeon_i2c_int_enable - enable the CORE interrupt
* @i2c: The struct octeon_i2c
*
* The interrupt will be asserted when there is non-STAT_IDLE state in
* the SW_TWSI_EOP_TWSI_STAT register.
*/
static void octeon_i2c_int_enable(struct octeon_i2c *i2c)
{
octeon_i2c_write_int(i2c, TWSI_INT_CORE_EN);
}
/* disable the CORE interrupt */
static void octeon_i2c_int_disable(struct octeon_i2c *i2c)
{
/* clear TS/ST/IFLG events */
octeon_i2c_write_int(i2c, 0);
}
/**
* octeon_i2c_int_enable78 - enable the CORE interrupt
* @i2c: The struct octeon_i2c
*
* The interrupt will be asserted when there is non-STAT_IDLE state in the
* SW_TWSI_EOP_TWSI_STAT register.
*/
static void octeon_i2c_int_enable78(struct octeon_i2c *i2c)
{
atomic_inc_return(&i2c->int_enable_cnt);
enable_irq(i2c->irq);
}
static void __octeon_i2c_irq_disable(atomic_t *cnt, int irq)
{
int count;
/*
* The interrupt can be disabled in two places, but we only
* want to make the disable_irq_nosync() call once, so keep
* track with the atomic variable.
*/
count = atomic_dec_if_positive(cnt);
if (count >= 0)
disable_irq_nosync(irq);
}
/* disable the CORE interrupt */
static void octeon_i2c_int_disable78(struct octeon_i2c *i2c)
{
__octeon_i2c_irq_disable(&i2c->int_enable_cnt, i2c->irq);
}
/**
* octeon_i2c_hlc_int_enable78 - enable the ST interrupt
* @i2c: The struct octeon_i2c
*
* The interrupt will be asserted when there is non-STAT_IDLE state in
* the SW_TWSI_EOP_TWSI_STAT register.
*/
static void octeon_i2c_hlc_int_enable78(struct octeon_i2c *i2c)
{
atomic_inc_return(&i2c->hlc_int_enable_cnt);
enable_irq(i2c->hlc_irq);
}
/* disable the ST interrupt */
static void octeon_i2c_hlc_int_disable78(struct octeon_i2c *i2c)
{
__octeon_i2c_irq_disable(&i2c->hlc_int_enable_cnt, i2c->hlc_irq);
}
/*
* Cleanup low-level state & enable high-level controller.
*/
static void octeon_i2c_hlc_enable(struct octeon_i2c *i2c)
{
int try = 0;
u64 val;
if (i2c->hlc_enabled)
return;
i2c->hlc_enabled = true;
while (1) {
val = octeon_i2c_ctl_read(i2c);
if (!(val & (TWSI_CTL_STA | TWSI_CTL_STP)))
break;
/* clear IFLG event */
if (val & TWSI_CTL_IFLG)
octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
if (try++ > 100) {
pr_err("%s: giving up\n", __func__);
break;
}
/* spin until any start/stop has finished */
udelay(10);
}
octeon_i2c_ctl_write(i2c, TWSI_CTL_CE | TWSI_CTL_AAK | TWSI_CTL_ENAB);
}
static void octeon_i2c_hlc_disable(struct octeon_i2c *i2c)
{
if (!i2c->hlc_enabled)
return;
i2c->hlc_enabled = false;
octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
}
/* interrupt service routine */
static irqreturn_t octeon_i2c_isr(int irq, void *dev_id)
{
struct octeon_i2c *i2c = dev_id;
i2c->int_disable(i2c);
wake_up(&i2c->queue);
return IRQ_HANDLED;
}
/* HLC interrupt service routine */
static irqreturn_t octeon_i2c_hlc_isr78(int irq, void *dev_id)
{
struct octeon_i2c *i2c = dev_id;
i2c->hlc_int_disable(i2c);
wake_up(&i2c->queue);
return IRQ_HANDLED;
}
static bool octeon_i2c_test_iflg(struct octeon_i2c *i2c)
{
return (octeon_i2c_ctl_read(i2c) & TWSI_CTL_IFLG);
}
static bool octeon_i2c_test_ready(struct octeon_i2c *i2c, bool *first)
{
if (octeon_i2c_test_iflg(i2c))
return true;
if (*first) {
*first = false;
return false;
}
/*
* IRQ has signaled an event but IFLG hasn't changed.
* Sleep and retry once.
*/
usleep_range(I2C_OCTEON_EVENT_WAIT, 2 * I2C_OCTEON_EVENT_WAIT);
return octeon_i2c_test_iflg(i2c);
}
/**
* octeon_i2c_wait - wait for the IFLG to be set
* @i2c: The struct octeon_i2c
*
* Returns 0 on success, otherwise a negative errno.
*/
static int octeon_i2c_wait(struct octeon_i2c *i2c)
{
long time_left;
bool first = 1;
i2c->int_enable(i2c);
time_left = wait_event_timeout(i2c->queue, octeon_i2c_test_ready(i2c, &first),
i2c->adap.timeout);
i2c->int_disable(i2c);
if (!time_left)
return -ETIMEDOUT;
return 0;
}
static int octeon_i2c_check_status(struct octeon_i2c *i2c, int final_read)
{
u8 stat = octeon_i2c_stat_read(i2c);
switch (stat) {
/* Everything is fine */
case STAT_IDLE:
case STAT_AD2W_ACK:
case STAT_RXADDR_ACK:
case STAT_TXADDR_ACK:
case STAT_TXDATA_ACK:
return 0;
/* ACK allowed on pre-terminal bytes only */
case STAT_RXDATA_ACK:
if (!final_read)
return 0;
return -EIO;
/* NAK allowed on terminal byte only */
case STAT_RXDATA_NAK:
if (final_read)
return 0;
return -EIO;
/* Arbitration lost */
case STAT_LOST_ARB_38:
case STAT_LOST_ARB_68:
case STAT_LOST_ARB_78:
case STAT_LOST_ARB_B0:
return -EAGAIN;
/* Being addressed as slave, should back off & listen */
case STAT_SLAVE_60:
case STAT_SLAVE_70:
case STAT_GENDATA_ACK:
case STAT_GENDATA_NAK:
return -EOPNOTSUPP;
/* Core busy as slave */
case STAT_SLAVE_80:
case STAT_SLAVE_88:
case STAT_SLAVE_A0:
case STAT_SLAVE_A8:
case STAT_SLAVE_LOST:
case STAT_SLAVE_NAK:
case STAT_SLAVE_ACK:
return -EOPNOTSUPP;
case STAT_TXDATA_NAK:
return -EIO;
case STAT_TXADDR_NAK:
case STAT_RXADDR_NAK:
case STAT_AD2W_NAK:
return -ENXIO;
default:
dev_err(i2c->dev, "unhandled state: %d\n", stat);
return -EIO;
}
}
static bool octeon_i2c_hlc_test_valid(struct octeon_i2c *i2c)
{
return (__raw_readq(i2c->twsi_base + SW_TWSI) & SW_TWSI_V) == 0;
}
static bool octeon_i2c_hlc_test_ready(struct octeon_i2c *i2c, bool *first)
{
/* check if valid bit is cleared */
if (octeon_i2c_hlc_test_valid(i2c))
return true;
if (*first) {
*first = false;
return false;
}
/*
* IRQ has signaled an event but valid bit isn't cleared.
* Sleep and retry once.
*/
usleep_range(I2C_OCTEON_EVENT_WAIT, 2 * I2C_OCTEON_EVENT_WAIT);
return octeon_i2c_hlc_test_valid(i2c);
}
static void octeon_i2c_hlc_int_enable(struct octeon_i2c *i2c)
{
octeon_i2c_write_int(i2c, TWSI_INT_ST_EN);
}
static void octeon_i2c_hlc_int_clear(struct octeon_i2c *i2c)
{
/* clear ST/TS events, listen for neither */
octeon_i2c_write_int(i2c, TWSI_INT_ST_INT | TWSI_INT_TS_INT);
}
/**
* octeon_i2c_hlc_wait - wait for an HLC operation to complete
* @i2c: The struct octeon_i2c
*
* Returns 0 on success, otherwise -ETIMEDOUT.
*/
static int octeon_i2c_hlc_wait(struct octeon_i2c *i2c)
{
bool first = 1;
int time_left;
i2c->hlc_int_enable(i2c);
time_left = wait_event_timeout(i2c->queue,
octeon_i2c_hlc_test_ready(i2c, &first),
i2c->adap.timeout);
i2c->hlc_int_disable(i2c);
if (!time_left) {
octeon_i2c_hlc_int_clear(i2c);
return -ETIMEDOUT;
}
return 0;
}
/* high-level-controller pure read of up to 8 bytes */
static int octeon_i2c_hlc_read(struct octeon_i2c *i2c, struct i2c_msg *msgs)
{
int i, j, ret = 0;
u64 cmd;
octeon_i2c_hlc_enable(i2c);
octeon_i2c_hlc_int_clear(i2c);
cmd = SW_TWSI_V | SW_TWSI_R | SW_TWSI_SOVR;
/* SIZE */
cmd |= (u64)(msgs[0].len - 1) << SW_TWSI_SIZE_SHIFT;
/* A */
cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
if (msgs[0].flags & I2C_M_TEN)
cmd |= SW_TWSI_OP_10;
else
cmd |= SW_TWSI_OP_7;
octeon_i2c_writeq_flush(cmd, i2c->twsi_base + SW_TWSI);
ret = octeon_i2c_hlc_wait(i2c);
if (ret)
goto err;
cmd = __raw_readq(i2c->twsi_base + SW_TWSI);
if ((cmd & SW_TWSI_R) == 0)
return -EAGAIN;
for (i = 0, j = msgs[0].len - 1; i < msgs[0].len && i < 4; i++, j--)
msgs[0].buf[j] = (cmd >> (8 * i)) & 0xff;
if (msgs[0].len > 4) {
cmd = __raw_readq(i2c->twsi_base + SW_TWSI_EXT);
for (i = 0; i < msgs[0].len - 4 && i < 4; i++, j--)
msgs[0].buf[j] = (cmd >> (8 * i)) & 0xff;
}
err:
return ret;
}
/* high-level-controller pure write of up to 8 bytes */
static int octeon_i2c_hlc_write(struct octeon_i2c *i2c, struct i2c_msg *msgs)
{
int i, j, ret = 0;
u64 cmd;
octeon_i2c_hlc_enable(i2c);
octeon_i2c_hlc_int_clear(i2c);
cmd = SW_TWSI_V | SW_TWSI_SOVR;
/* SIZE */
cmd |= (u64)(msgs[0].len - 1) << SW_TWSI_SIZE_SHIFT;
/* A */
cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
if (msgs[0].flags & I2C_M_TEN)
cmd |= SW_TWSI_OP_10;
else
cmd |= SW_TWSI_OP_7;
for (i = 0, j = msgs[0].len - 1; i < msgs[0].len && i < 4; i++, j--)
cmd |= (u64)msgs[0].buf[j] << (8 * i);
if (msgs[0].len > 4) {
u64 ext = 0;
for (i = 0; i < msgs[0].len - 4 && i < 4; i++, j--)
ext |= (u64)msgs[0].buf[j] << (8 * i);
octeon_i2c_writeq_flush(ext, i2c->twsi_base + SW_TWSI_EXT);
}
octeon_i2c_writeq_flush(cmd, i2c->twsi_base + SW_TWSI);
ret = octeon_i2c_hlc_wait(i2c);
if (ret)
goto err;
cmd = __raw_readq(i2c->twsi_base + SW_TWSI);
if ((cmd & SW_TWSI_R) == 0)
return -EAGAIN;
ret = octeon_i2c_check_status(i2c, false);
err:
return ret;
}
/* high-level-controller composite write+read, msg0=addr, msg1=data */
static int octeon_i2c_hlc_comp_read(struct octeon_i2c *i2c, struct i2c_msg *msgs)
{
int i, j, ret = 0;
u64 cmd;
octeon_i2c_hlc_enable(i2c);
cmd = SW_TWSI_V | SW_TWSI_R | SW_TWSI_SOVR;
/* SIZE */
cmd |= (u64)(msgs[1].len - 1) << SW_TWSI_SIZE_SHIFT;
/* A */
cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
if (msgs[0].flags & I2C_M_TEN)
cmd |= SW_TWSI_OP_10_IA;
else
cmd |= SW_TWSI_OP_7_IA;
if (msgs[0].len == 2) {
u64 ext = 0;
cmd |= SW_TWSI_EIA;
ext = (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
cmd |= (u64)msgs[0].buf[1] << SW_TWSI_IA_SHIFT;
octeon_i2c_writeq_flush(ext, i2c->twsi_base + SW_TWSI_EXT);
} else {
cmd |= (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
}
octeon_i2c_hlc_int_clear(i2c);
octeon_i2c_writeq_flush(cmd, i2c->twsi_base + SW_TWSI);
ret = octeon_i2c_hlc_wait(i2c);
if (ret)
goto err;
cmd = __raw_readq(i2c->twsi_base + SW_TWSI);
if ((cmd & SW_TWSI_R) == 0)
return -EAGAIN;
for (i = 0, j = msgs[1].len - 1; i < msgs[1].len && i < 4; i++, j--)
msgs[1].buf[j] = (cmd >> (8 * i)) & 0xff;
if (msgs[1].len > 4) {
cmd = __raw_readq(i2c->twsi_base + SW_TWSI_EXT);
for (i = 0; i < msgs[1].len - 4 && i < 4; i++, j--)
msgs[1].buf[j] = (cmd >> (8 * i)) & 0xff;
}
err:
return ret;
}
/* high-level-controller composite write+write, m[0]len<=2, m[1]len<=8 */
static int octeon_i2c_hlc_comp_write(struct octeon_i2c *i2c, struct i2c_msg *msgs)
{
bool set_ext = false;
int i, j, ret = 0;
u64 cmd, ext = 0;
octeon_i2c_hlc_enable(i2c);
cmd = SW_TWSI_V | SW_TWSI_SOVR;
/* SIZE */
cmd |= (u64)(msgs[1].len - 1) << SW_TWSI_SIZE_SHIFT;
/* A */
cmd |= (u64)(msgs[0].addr & 0x7full) << SW_TWSI_ADDR_SHIFT;
if (msgs[0].flags & I2C_M_TEN)
cmd |= SW_TWSI_OP_10_IA;
else
cmd |= SW_TWSI_OP_7_IA;
if (msgs[0].len == 2) {
cmd |= SW_TWSI_EIA;
ext |= (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
set_ext = true;
cmd |= (u64)msgs[0].buf[1] << SW_TWSI_IA_SHIFT;
} else {
cmd |= (u64)msgs[0].buf[0] << SW_TWSI_IA_SHIFT;
}
for (i = 0, j = msgs[1].len - 1; i < msgs[1].len && i < 4; i++, j--)
cmd |= (u64)msgs[1].buf[j] << (8 * i);
if (msgs[1].len > 4) {
for (i = 0; i < msgs[1].len - 4 && i < 4; i++, j--)
ext |= (u64)msgs[1].buf[j] << (8 * i);
set_ext = true;
}
if (set_ext)
octeon_i2c_writeq_flush(ext, i2c->twsi_base + SW_TWSI_EXT);
octeon_i2c_hlc_int_clear(i2c);
octeon_i2c_writeq_flush(cmd, i2c->twsi_base + SW_TWSI);
ret = octeon_i2c_hlc_wait(i2c);
if (ret)
goto err;
cmd = __raw_readq(i2c->twsi_base + SW_TWSI);
if ((cmd & SW_TWSI_R) == 0)
return -EAGAIN;
ret = octeon_i2c_check_status(i2c, false);
err:
return ret;
}
/* calculate and set clock divisors */
static void octeon_i2c_set_clock(struct octeon_i2c *i2c)
{
int tclk, thp_base, inc, thp_idx, mdiv_idx, ndiv_idx, foscl, diff;
int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = 1000000;
for (ndiv_idx = 0; ndiv_idx < 8 && delta_hz != 0; ndiv_idx++) {
/*
* An mdiv value of less than 2 seems to not work well
* with ds1337 RTCs, so we constrain it to larger values.
*/
for (mdiv_idx = 15; mdiv_idx >= 2 && delta_hz != 0; mdiv_idx--) {
/*
* For given ndiv and mdiv values check the
* two closest thp values.
*/
tclk = i2c->twsi_freq * (mdiv_idx + 1) * 10;
tclk *= (1 << ndiv_idx);
thp_base = (i2c->sys_freq / (tclk * 2)) - 1;
for (inc = 0; inc <= 1; inc++) {
thp_idx = thp_base + inc;
if (thp_idx < 5 || thp_idx > 0xff)
continue;
foscl = i2c->sys_freq / (2 * (thp_idx + 1));
foscl = foscl / (1 << ndiv_idx);
foscl = foscl / (mdiv_idx + 1) / 10;
diff = abs(foscl - i2c->twsi_freq);
if (diff < delta_hz) {
delta_hz = diff;
thp = thp_idx;
mdiv = mdiv_idx;
ndiv = ndiv_idx;
}
}
}
}
octeon_i2c_reg_write(i2c, SW_TWSI_OP_TWSI_CLK, thp);
octeon_i2c_reg_write(i2c, SW_TWSI_EOP_TWSI_CLKCTL, (mdiv << 3) | ndiv);
}
static int octeon_i2c_init_lowlevel(struct octeon_i2c *i2c)
{
u8 status = 0;
int tries;
/* reset controller */
octeon_i2c_reg_write(i2c, SW_TWSI_EOP_TWSI_RST, 0);
for (tries = 10; tries && status != STAT_IDLE; tries--) {
udelay(1);
status = octeon_i2c_stat_read(i2c);
if (status == STAT_IDLE)
break;
}
if (status != STAT_IDLE) {
dev_err(i2c->dev, "%s: TWSI_RST failed! (0x%x)\n",
__func__, status);
return -EIO;
}
/* toggle twice to force both teardowns */
octeon_i2c_hlc_enable(i2c);
octeon_i2c_hlc_disable(i2c);
return 0;
}
static int octeon_i2c_recovery(struct octeon_i2c *i2c)
{
int ret;
ret = i2c_recover_bus(&i2c->adap);
if (ret)
/* recover failed, try hardware re-init */
ret = octeon_i2c_init_lowlevel(i2c);
return ret;
}
/**
* octeon_i2c_start - send START to the bus
* @i2c: The struct octeon_i2c
*
* Returns 0 on success, otherwise a negative errno.
*/
static int octeon_i2c_start(struct octeon_i2c *i2c)
{
int ret;
u8 stat;
octeon_i2c_hlc_disable(i2c);
octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_STA);
ret = octeon_i2c_wait(i2c);
if (ret)
goto error;
stat = octeon_i2c_stat_read(i2c);
if (stat == STAT_START || stat == STAT_REP_START)
/* START successful, bail out */
return 0;
error:
/* START failed, try to recover */
ret = octeon_i2c_recovery(i2c);
return (ret) ? ret : -EAGAIN;
}
/* send STOP to the bus */
static void octeon_i2c_stop(struct octeon_i2c *i2c)
{
octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_STP);
}
/**
* octeon_i2c_write - send data to the bus via low-level controller
* @i2c: The struct octeon_i2c
* @target: Target address
* @data: Pointer to the data to be sent
* @length: Length of the data
*
* The address is sent over the bus, then the data.
*
* Returns 0 on success, otherwise a negative errno.
*/
static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
const u8 *data, int length)
{
int i, result;
octeon_i2c_data_write(i2c, target << 1);
octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
for (i = 0; i < length; i++) {
result = octeon_i2c_check_status(i2c, false);
if (result)
return result;
octeon_i2c_data_write(i2c, data[i]);
octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
}
return 0;
}
/**
* octeon_i2c_read - receive data from the bus via low-level controller
* @i2c: The struct octeon_i2c
* @target: Target address
* @data: Pointer to the location to store the data
* @rlength: Length of the data
* @recv_len: flag for length byte
*
* The address is sent over the bus, then the data is read.
*
* Returns 0 on success, otherwise a negative errno.
*/
static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
u8 *data, u16 *rlength, bool recv_len)
{
int i, result, length = *rlength;
bool final_read = false;
octeon_i2c_data_write(i2c, (target << 1) | 1);
octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
/* address OK ? */
result = octeon_i2c_check_status(i2c, false);
if (result)
return result;
for (i = 0; i < length; i++) {
/* for the last byte TWSI_CTL_AAK must not be set */
if (i + 1 == length)
final_read = true;
/* clear iflg to allow next event */
if (final_read)
octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
else
octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_AAK);
result = octeon_i2c_wait(i2c);
if (result)
return result;
data[i] = octeon_i2c_data_read(i2c);
if (recv_len && i == 0) {
if (data[i] > I2C_SMBUS_BLOCK_MAX + 1) {
dev_err(i2c->dev,
"%s: read len > I2C_SMBUS_BLOCK_MAX %d\n",
__func__, data[i]);
return -EPROTO;
}
length += data[i];
}
result = octeon_i2c_check_status(i2c, final_read);
if (result)
return result;
}
*rlength = length;
return 0;
}
/**
* octeon_i2c_xfer - The driver's master_xfer function
* @adap: Pointer to the i2c_adapter structure
* @msgs: Pointer to the messages to be processed
* @num: Length of the MSGS array
*
* Returns the number of messages processed, or a negative errno on failure.
*/
static int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
struct octeon_i2c *i2c = i2c_get_adapdata(adap);
int i, ret = 0;
if (num == 1) {
if (msgs[0].len > 0 && msgs[0].len <= 8) {
if (msgs[0].flags & I2C_M_RD)
ret = octeon_i2c_hlc_read(i2c, msgs);
else
ret = octeon_i2c_hlc_write(i2c, msgs);
goto out;
}
} else if (num == 2) {
if ((msgs[0].flags & I2C_M_RD) == 0 &&
(msgs[1].flags & I2C_M_RECV_LEN) == 0 &&
msgs[0].len > 0 && msgs[0].len <= 2 &&
msgs[1].len > 0 && msgs[1].len <= 8 &&
msgs[0].addr == msgs[1].addr) {
if (msgs[1].flags & I2C_M_RD)
ret = octeon_i2c_hlc_comp_read(i2c, msgs);
else
ret = octeon_i2c_hlc_comp_write(i2c, msgs);
goto out;
}
}
for (i = 0; ret == 0 && i < num; i++) {
struct i2c_msg *pmsg = &msgs[i];
/* zero-length messages are not supported */
if (!pmsg->len) {
ret = -EOPNOTSUPP;
break;
}
ret = octeon_i2c_start(i2c);
if (ret)
return ret;
if (pmsg->flags & I2C_M_RD)
ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
&pmsg->len, pmsg->flags & I2C_M_RECV_LEN);
else
ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf,
pmsg->len);
}
octeon_i2c_stop(i2c);
out:
return (ret != 0) ? ret : num;
}
static int octeon_i2c_get_scl(struct i2c_adapter *adap)
{
struct octeon_i2c *i2c = i2c_get_adapdata(adap);
u64 state;
state = octeon_i2c_read_int(i2c);
return state & TWSI_INT_SCL;
}
static void octeon_i2c_set_scl(struct i2c_adapter *adap, int val)
{
struct octeon_i2c *i2c = i2c_get_adapdata(adap);
octeon_i2c_write_int(i2c, TWSI_INT_SCL_OVR);
}
static int octeon_i2c_get_sda(struct i2c_adapter *adap)
{
struct octeon_i2c *i2c = i2c_get_adapdata(adap);
u64 state;
state = octeon_i2c_read_int(i2c);
return state & TWSI_INT_SDA;
}
static void octeon_i2c_prepare_recovery(struct i2c_adapter *adap)
{
struct octeon_i2c *i2c = i2c_get_adapdata(adap);
/*
* The stop resets the state machine, does not _transmit_ STOP unless
* engine was active.
*/
octeon_i2c_stop(i2c);
octeon_i2c_hlc_disable(i2c);
octeon_i2c_write_int(i2c, 0);
}
static void octeon_i2c_unprepare_recovery(struct i2c_adapter *adap)
{
struct octeon_i2c *i2c = i2c_get_adapdata(adap);
octeon_i2c_write_int(i2c, 0);
}
static struct i2c_bus_recovery_info octeon_i2c_recovery_info = {
.recover_bus = i2c_generic_scl_recovery,
.get_scl = octeon_i2c_get_scl,
.set_scl = octeon_i2c_set_scl,
.get_sda = octeon_i2c_get_sda,
.prepare_recovery = octeon_i2c_prepare_recovery,
.unprepare_recovery = octeon_i2c_unprepare_recovery,
};
static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_SMBUS_BLOCK_PROC_CALL;
}
static const struct i2c_algorithm octeon_i2c_algo = {
.master_xfer = octeon_i2c_xfer,
.functionality = octeon_i2c_functionality,
};
static struct i2c_adapter octeon_i2c_ops = {
.owner = THIS_MODULE,
.name = "OCTEON adapter",
.algo = &octeon_i2c_algo,
};
static int octeon_i2c_probe(struct platform_device *pdev)
{
struct device_node *node = pdev->dev.of_node;
int irq, result = 0, hlc_irq = 0;
struct resource *res_mem;
struct octeon_i2c *i2c;
bool cn78xx_style;
cn78xx_style = of_device_is_compatible(node, "cavium,octeon-7890-twsi");
if (cn78xx_style) {
hlc_irq = platform_get_irq(pdev, 0);
if (hlc_irq < 0)
return hlc_irq;
irq = platform_get_irq(pdev, 2);
if (irq < 0)
return irq;
} else {
/* All adaptors have an irq. */
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
}
i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
if (!i2c) {
result = -ENOMEM;
goto out;
}
i2c->dev = &pdev->dev;
res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
i2c->twsi_base = devm_ioremap_resource(&pdev->dev, res_mem);
if (IS_ERR(i2c->twsi_base)) {
result = PTR_ERR(i2c->twsi_base);
goto out;
}
/*
* "clock-rate" is a legacy binding, the official binding is
* "clock-frequency". Try the official one first and then
* fall back if it doesn't exist.
*/
if (of_property_read_u32(node, "clock-frequency", &i2c->twsi_freq) &&
of_property_read_u32(node, "clock-rate", &i2c->twsi_freq)) {
dev_err(i2c->dev,
"no I2C 'clock-rate' or 'clock-frequency' property\n");
result = -ENXIO;
goto out;
}
i2c->sys_freq = octeon_get_io_clock_rate();
init_waitqueue_head(&i2c->queue);
i2c->irq = irq;
if (cn78xx_style) {
i2c->hlc_irq = hlc_irq;
i2c->int_enable = octeon_i2c_int_enable78;
i2c->int_disable = octeon_i2c_int_disable78;
i2c->hlc_int_enable = octeon_i2c_hlc_int_enable78;
i2c->hlc_int_disable = octeon_i2c_hlc_int_disable78;
irq_set_status_flags(i2c->irq, IRQ_NOAUTOEN);
irq_set_status_flags(i2c->hlc_irq, IRQ_NOAUTOEN);
result = devm_request_irq(&pdev->dev, i2c->hlc_irq,
octeon_i2c_hlc_isr78, 0,
DRV_NAME, i2c);
if (result < 0) {
dev_err(i2c->dev, "failed to attach interrupt\n");
goto out;
}
} else {
i2c->int_enable = octeon_i2c_int_enable;
i2c->int_disable = octeon_i2c_int_disable;
i2c->hlc_int_enable = octeon_i2c_hlc_int_enable;
i2c->hlc_int_disable = octeon_i2c_int_disable;
}
result = devm_request_irq(&pdev->dev, i2c->irq,
octeon_i2c_isr, 0, DRV_NAME, i2c);
if (result < 0) {
dev_err(i2c->dev, "failed to attach interrupt\n");
goto out;
}
result = octeon_i2c_init_lowlevel(i2c);
if (result) {
dev_err(i2c->dev, "init low level failed\n");
goto out;
}
octeon_i2c_set_clock(i2c);
i2c->adap = octeon_i2c_ops;
i2c->adap.timeout = msecs_to_jiffies(2);
i2c->adap.retries = 5;
i2c->adap.bus_recovery_info = &octeon_i2c_recovery_info;
i2c->adap.dev.parent = &pdev->dev;
i2c->adap.dev.of_node = node;
i2c_set_adapdata(&i2c->adap, i2c);
platform_set_drvdata(pdev, i2c);
result = i2c_add_adapter(&i2c->adap);
if (result < 0) {
dev_err(i2c->dev, "failed to add adapter\n");
goto out;
}
dev_info(i2c->dev, "probed\n");
return 0;
out:
return result;
};
static int octeon_i2c_remove(struct platform_device *pdev)
{
struct octeon_i2c *i2c = platform_get_drvdata(pdev);
i2c_del_adapter(&i2c->adap);
return 0;
};
static const struct of_device_id octeon_i2c_match[] = {
{ .compatible = "cavium,octeon-3860-twsi", },
{ .compatible = "cavium,octeon-7890-twsi", },
{},
};
MODULE_DEVICE_TABLE(of, octeon_i2c_match);
static struct platform_driver octeon_i2c_driver = {
.probe = octeon_i2c_probe,
.remove = octeon_i2c_remove,
.driver = {
.name = DRV_NAME,
.of_match_table = octeon_i2c_match,
},
};
module_platform_driver(octeon_i2c_driver);
MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
MODULE_LICENSE("GPL");
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