blob: e0c256922d4f177b30c4d7aafe39d9ff9f617ff9 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0+
/*
* FSI-attached I2C master algorithm
*
* Copyright 2018 IBM Corporation
*
* 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/bitfield.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fsi.h>
#include <linux/i2c.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/slab.h>
#define FSI_ENGID_I2C 0x7
#define I2C_DEFAULT_CLK_DIV 6
/* i2c registers */
#define I2C_FSI_FIFO 0x00
#define I2C_FSI_CMD 0x04
#define I2C_FSI_MODE 0x08
#define I2C_FSI_WATER_MARK 0x0C
#define I2C_FSI_INT_MASK 0x10
#define I2C_FSI_INT_COND 0x14
#define I2C_FSI_OR_INT_MASK 0x14
#define I2C_FSI_INTS 0x18
#define I2C_FSI_AND_INT_MASK 0x18
#define I2C_FSI_STAT 0x1C
#define I2C_FSI_RESET_I2C 0x1C
#define I2C_FSI_ESTAT 0x20
#define I2C_FSI_RESET_ERR 0x20
#define I2C_FSI_RESID_LEN 0x24
#define I2C_FSI_SET_SCL 0x24
#define I2C_FSI_PORT_BUSY 0x28
#define I2C_FSI_RESET_SCL 0x2C
#define I2C_FSI_SET_SDA 0x30
#define I2C_FSI_RESET_SDA 0x34
/* cmd register */
#define I2C_CMD_WITH_START BIT(31)
#define I2C_CMD_WITH_ADDR BIT(30)
#define I2C_CMD_RD_CONT BIT(29)
#define I2C_CMD_WITH_STOP BIT(28)
#define I2C_CMD_FORCELAUNCH BIT(27)
#define I2C_CMD_ADDR GENMASK(23, 17)
#define I2C_CMD_READ BIT(16)
#define I2C_CMD_LEN GENMASK(15, 0)
/* mode register */
#define I2C_MODE_CLKDIV GENMASK(31, 16)
#define I2C_MODE_PORT GENMASK(15, 10)
#define I2C_MODE_ENHANCED BIT(3)
#define I2C_MODE_DIAG BIT(2)
#define I2C_MODE_PACE_ALLOW BIT(1)
#define I2C_MODE_WRAP BIT(0)
/* watermark register */
#define I2C_WATERMARK_HI GENMASK(15, 12)
#define I2C_WATERMARK_LO GENMASK(7, 4)
#define I2C_FIFO_HI_LVL 4
#define I2C_FIFO_LO_LVL 4
/* interrupt register */
#define I2C_INT_INV_CMD BIT(15)
#define I2C_INT_PARITY BIT(14)
#define I2C_INT_BE_OVERRUN BIT(13)
#define I2C_INT_BE_ACCESS BIT(12)
#define I2C_INT_LOST_ARB BIT(11)
#define I2C_INT_NACK BIT(10)
#define I2C_INT_DAT_REQ BIT(9)
#define I2C_INT_CMD_COMP BIT(8)
#define I2C_INT_STOP_ERR BIT(7)
#define I2C_INT_BUSY BIT(6)
#define I2C_INT_IDLE BIT(5)
/* status register */
#define I2C_STAT_INV_CMD BIT(31)
#define I2C_STAT_PARITY BIT(30)
#define I2C_STAT_BE_OVERRUN BIT(29)
#define I2C_STAT_BE_ACCESS BIT(28)
#define I2C_STAT_LOST_ARB BIT(27)
#define I2C_STAT_NACK BIT(26)
#define I2C_STAT_DAT_REQ BIT(25)
#define I2C_STAT_CMD_COMP BIT(24)
#define I2C_STAT_STOP_ERR BIT(23)
#define I2C_STAT_MAX_PORT GENMASK(19, 16)
#define I2C_STAT_ANY_INT BIT(15)
#define I2C_STAT_SCL_IN BIT(11)
#define I2C_STAT_SDA_IN BIT(10)
#define I2C_STAT_PORT_BUSY BIT(9)
#define I2C_STAT_SELF_BUSY BIT(8)
#define I2C_STAT_FIFO_COUNT GENMASK(7, 0)
#define I2C_STAT_ERR (I2C_STAT_INV_CMD | \
I2C_STAT_PARITY | \
I2C_STAT_BE_OVERRUN | \
I2C_STAT_BE_ACCESS | \
I2C_STAT_LOST_ARB | \
I2C_STAT_NACK | \
I2C_STAT_STOP_ERR)
#define I2C_STAT_ANY_RESP (I2C_STAT_ERR | \
I2C_STAT_DAT_REQ | \
I2C_STAT_CMD_COMP)
/* extended status register */
#define I2C_ESTAT_FIFO_SZ GENMASK(31, 24)
#define I2C_ESTAT_SCL_IN_SY BIT(15)
#define I2C_ESTAT_SDA_IN_SY BIT(14)
#define I2C_ESTAT_S_SCL BIT(13)
#define I2C_ESTAT_S_SDA BIT(12)
#define I2C_ESTAT_M_SCL BIT(11)
#define I2C_ESTAT_M_SDA BIT(10)
#define I2C_ESTAT_HI_WATER BIT(9)
#define I2C_ESTAT_LO_WATER BIT(8)
#define I2C_ESTAT_PORT_BUSY BIT(7)
#define I2C_ESTAT_SELF_BUSY BIT(6)
#define I2C_ESTAT_VERSION GENMASK(4, 0)
/* port busy register */
#define I2C_PORT_BUSY_RESET BIT(31)
/* wait for command complete or data request */
#define I2C_CMD_SLEEP_MAX_US 500
#define I2C_CMD_SLEEP_MIN_US 50
/* wait after reset; choose time from legacy driver */
#define I2C_RESET_SLEEP_MAX_US 2000
#define I2C_RESET_SLEEP_MIN_US 1000
/* choose timeout length from legacy driver; it's well tested */
#define I2C_ABORT_TIMEOUT msecs_to_jiffies(100)
struct fsi_i2c_master {
struct fsi_device *fsi;
u8 fifo_size;
struct list_head ports;
struct mutex lock;
};
struct fsi_i2c_port {
struct list_head list;
struct i2c_adapter adapter;
struct fsi_i2c_master *master;
u16 port;
u16 xfrd;
};
static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
u32 *data)
{
int rc;
__be32 data_be;
rc = fsi_device_read(fsi, reg, &data_be, sizeof(data_be));
if (rc)
return rc;
*data = be32_to_cpu(data_be);
return 0;
}
static int fsi_i2c_write_reg(struct fsi_device *fsi, unsigned int reg,
u32 *data)
{
__be32 data_be = cpu_to_be32p(data);
return fsi_device_write(fsi, reg, &data_be, sizeof(data_be));
}
static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c)
{
int rc;
u32 mode = I2C_MODE_ENHANCED, extended_status, watermark;
u32 interrupt = 0;
/* since we use polling, disable interrupts */
rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_INT_MASK, &interrupt);
if (rc)
return rc;
mode |= FIELD_PREP(I2C_MODE_CLKDIV, I2C_DEFAULT_CLK_DIV);
rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
if (rc)
return rc;
rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_ESTAT, &extended_status);
if (rc)
return rc;
i2c->fifo_size = FIELD_GET(I2C_ESTAT_FIFO_SZ, extended_status);
watermark = FIELD_PREP(I2C_WATERMARK_HI,
i2c->fifo_size - I2C_FIFO_HI_LVL);
watermark |= FIELD_PREP(I2C_WATERMARK_LO, I2C_FIFO_LO_LVL);
return fsi_i2c_write_reg(i2c->fsi, I2C_FSI_WATER_MARK, &watermark);
}
static int fsi_i2c_set_port(struct fsi_i2c_port *port)
{
int rc;
struct fsi_device *fsi = port->master->fsi;
u32 mode, dummy = 0;
rc = fsi_i2c_read_reg(fsi, I2C_FSI_MODE, &mode);
if (rc)
return rc;
if (FIELD_GET(I2C_MODE_PORT, mode) == port->port)
return 0;
mode = (mode & ~I2C_MODE_PORT) | FIELD_PREP(I2C_MODE_PORT, port->port);
rc = fsi_i2c_write_reg(fsi, I2C_FSI_MODE, &mode);
if (rc)
return rc;
/* reset engine when port is changed */
return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
}
static int fsi_i2c_start(struct fsi_i2c_port *port, struct i2c_msg *msg,
bool stop)
{
struct fsi_i2c_master *i2c = port->master;
u32 cmd = I2C_CMD_WITH_START | I2C_CMD_WITH_ADDR;
port->xfrd = 0;
if (msg->flags & I2C_M_RD)
cmd |= I2C_CMD_READ;
if (stop || msg->flags & I2C_M_STOP)
cmd |= I2C_CMD_WITH_STOP;
cmd |= FIELD_PREP(I2C_CMD_ADDR, msg->addr);
cmd |= FIELD_PREP(I2C_CMD_LEN, msg->len);
return fsi_i2c_write_reg(i2c->fsi, I2C_FSI_CMD, &cmd);
}
static int fsi_i2c_get_op_bytes(int op_bytes)
{
/* fsi is limited to max 4 byte aligned ops */
if (op_bytes > 4)
return 4;
else if (op_bytes == 3)
return 2;
return op_bytes;
}
static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
u8 fifo_count)
{
int write;
int rc;
struct fsi_i2c_master *i2c = port->master;
int bytes_to_write = i2c->fifo_size - fifo_count;
int bytes_remaining = msg->len - port->xfrd;
bytes_to_write = min(bytes_to_write, bytes_remaining);
while (bytes_to_write) {
write = fsi_i2c_get_op_bytes(bytes_to_write);
rc = fsi_device_write(i2c->fsi, I2C_FSI_FIFO,
&msg->buf[port->xfrd], write);
if (rc)
return rc;
port->xfrd += write;
bytes_to_write -= write;
}
return 0;
}
static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
u8 fifo_count)
{
int read;
int rc;
struct fsi_i2c_master *i2c = port->master;
int bytes_to_read;
int xfr_remaining = msg->len - port->xfrd;
u32 dummy;
bytes_to_read = min_t(int, fifo_count, xfr_remaining);
while (bytes_to_read) {
read = fsi_i2c_get_op_bytes(bytes_to_read);
if (xfr_remaining) {
rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO,
&msg->buf[port->xfrd], read);
if (rc)
return rc;
port->xfrd += read;
xfr_remaining -= read;
} else {
/* no more buffer but data in fifo, need to clear it */
rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO, &dummy,
read);
if (rc)
return rc;
}
bytes_to_read -= read;
}
return 0;
}
static int fsi_i2c_get_scl(struct i2c_adapter *adap)
{
u32 stat = 0;
struct fsi_i2c_port *port = adap->algo_data;
struct fsi_i2c_master *i2c = port->master;
fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
return !!(stat & I2C_STAT_SCL_IN);
}
static void fsi_i2c_set_scl(struct i2c_adapter *adap, int val)
{
u32 dummy = 0;
struct fsi_i2c_port *port = adap->algo_data;
struct fsi_i2c_master *i2c = port->master;
if (val)
fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
else
fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
}
static int fsi_i2c_get_sda(struct i2c_adapter *adap)
{
u32 stat = 0;
struct fsi_i2c_port *port = adap->algo_data;
struct fsi_i2c_master *i2c = port->master;
fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
return !!(stat & I2C_STAT_SDA_IN);
}
static void fsi_i2c_set_sda(struct i2c_adapter *adap, int val)
{
u32 dummy = 0;
struct fsi_i2c_port *port = adap->algo_data;
struct fsi_i2c_master *i2c = port->master;
if (val)
fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
else
fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
}
static void fsi_i2c_prepare_recovery(struct i2c_adapter *adap)
{
int rc;
u32 mode;
struct fsi_i2c_port *port = adap->algo_data;
struct fsi_i2c_master *i2c = port->master;
rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
if (rc)
return;
mode |= I2C_MODE_DIAG;
fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
}
static void fsi_i2c_unprepare_recovery(struct i2c_adapter *adap)
{
int rc;
u32 mode;
struct fsi_i2c_port *port = adap->algo_data;
struct fsi_i2c_master *i2c = port->master;
rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
if (rc)
return;
mode &= ~I2C_MODE_DIAG;
fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
}
static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c,
struct fsi_i2c_port *port)
{
int rc;
u32 stat, dummy = 0;
/* force bus reset, ignore errors */
i2c_recover_bus(&port->adapter);
/* reset errors */
rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
if (rc)
return rc;
/* wait for command complete */
usleep_range(I2C_RESET_SLEEP_MIN_US, I2C_RESET_SLEEP_MAX_US);
rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
if (rc)
return rc;
if (stat & I2C_STAT_CMD_COMP)
return 0;
/* failed to get command complete; reset engine again */
rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
if (rc)
return rc;
/* re-init engine again */
return fsi_i2c_dev_init(i2c);
}
static int fsi_i2c_reset_engine(struct fsi_i2c_master *i2c, u16 port)
{
int rc;
u32 mode, dummy = 0;
/* reset engine */
rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
if (rc)
return rc;
/* re-init engine */
rc = fsi_i2c_dev_init(i2c);
if (rc)
return rc;
rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
if (rc)
return rc;
/* set port; default after reset is 0 */
if (port) {
mode &= ~I2C_MODE_PORT;
mode |= FIELD_PREP(I2C_MODE_PORT, port);
rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
if (rc)
return rc;
}
/* reset busy register; hw workaround */
dummy = I2C_PORT_BUSY_RESET;
rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);
if (rc)
return rc;
return 0;
}
static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
{
int rc;
unsigned long start;
u32 cmd = I2C_CMD_WITH_STOP;
u32 stat;
struct fsi_i2c_master *i2c = port->master;
struct fsi_device *fsi = i2c->fsi;
rc = fsi_i2c_reset_engine(i2c, port->port);
if (rc)
return rc;
rc = fsi_i2c_read_reg(fsi, I2C_FSI_STAT, &stat);
if (rc)
return rc;
/* if sda is low, peform full bus reset */
if (!(stat & I2C_STAT_SDA_IN)) {
rc = fsi_i2c_reset_bus(i2c, port);
if (rc)
return rc;
}
/* skip final stop command for these errors */
if (status & (I2C_STAT_PARITY | I2C_STAT_LOST_ARB | I2C_STAT_STOP_ERR))
return 0;
/* write stop command */
rc = fsi_i2c_write_reg(fsi, I2C_FSI_CMD, &cmd);
if (rc)
return rc;
/* wait until we see command complete in the master */
start = jiffies;
do {
rc = fsi_i2c_read_reg(fsi, I2C_FSI_STAT, &status);
if (rc)
return rc;
if (status & I2C_STAT_CMD_COMP)
return 0;
usleep_range(I2C_CMD_SLEEP_MIN_US, I2C_CMD_SLEEP_MAX_US);
} while (time_after(start + I2C_ABORT_TIMEOUT, jiffies));
return -ETIMEDOUT;
}
static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
struct i2c_msg *msg, u32 status)
{
int rc;
u8 fifo_count;
if (status & I2C_STAT_ERR) {
rc = fsi_i2c_abort(port, status);
if (rc)
return rc;
if (status & I2C_STAT_INV_CMD)
return -EINVAL;
if (status & (I2C_STAT_PARITY | I2C_STAT_BE_OVERRUN |
I2C_STAT_BE_ACCESS))
return -EPROTO;
if (status & I2C_STAT_NACK)
return -ENXIO;
if (status & I2C_STAT_LOST_ARB)
return -EAGAIN;
if (status & I2C_STAT_STOP_ERR)
return -EBADMSG;
return -EIO;
}
if (status & I2C_STAT_DAT_REQ) {
fifo_count = FIELD_GET(I2C_STAT_FIFO_COUNT, status);
if (msg->flags & I2C_M_RD)
return fsi_i2c_read_fifo(port, msg, fifo_count);
return fsi_i2c_write_fifo(port, msg, fifo_count);
}
if (status & I2C_STAT_CMD_COMP) {
if (port->xfrd < msg->len)
return -ENODATA;
return msg->len;
}
return 0;
}
static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
unsigned long timeout)
{
u32 status = 0;
int rc;
unsigned long start = jiffies;
do {
rc = fsi_i2c_read_reg(port->master->fsi, I2C_FSI_STAT,
&status);
if (rc)
return rc;
if (status & I2C_STAT_ANY_RESP) {
rc = fsi_i2c_handle_status(port, msg, status);
if (rc < 0)
return rc;
/* cmd complete and all data xfrd */
if (rc == msg->len)
return 0;
/* need to xfr more data, but maybe don't need wait */
continue;
}
usleep_range(I2C_CMD_SLEEP_MIN_US, I2C_CMD_SLEEP_MAX_US);
} while (time_after(start + timeout, jiffies));
return -ETIMEDOUT;
}
static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
int i, rc;
unsigned long start_time;
struct fsi_i2c_port *port = adap->algo_data;
struct fsi_i2c_master *master = port->master;
struct i2c_msg *msg;
mutex_lock(&master->lock);
rc = fsi_i2c_set_port(port);
if (rc)
goto unlock;
for (i = 0; i < num; i++) {
msg = msgs + i;
start_time = jiffies;
rc = fsi_i2c_start(port, msg, i == num - 1);
if (rc)
goto unlock;
rc = fsi_i2c_wait(port, msg,
adap->timeout - (jiffies - start_time));
if (rc)
goto unlock;
}
unlock:
mutex_unlock(&master->lock);
return rc ? : num;
}
static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_PROTOCOL_MANGLING |
I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
}
static struct i2c_bus_recovery_info fsi_i2c_bus_recovery_info = {
.recover_bus = i2c_generic_scl_recovery,
.get_scl = fsi_i2c_get_scl,
.set_scl = fsi_i2c_set_scl,
.get_sda = fsi_i2c_get_sda,
.set_sda = fsi_i2c_set_sda,
.prepare_recovery = fsi_i2c_prepare_recovery,
.unprepare_recovery = fsi_i2c_unprepare_recovery,
};
static const struct i2c_algorithm fsi_i2c_algorithm = {
.master_xfer = fsi_i2c_xfer,
.functionality = fsi_i2c_functionality,
};
static struct device_node *fsi_i2c_find_port_of_node(struct device_node *fsi,
int port)
{
struct device_node *np;
u32 port_no;
int rc;
for_each_child_of_node(fsi, np) {
rc = of_property_read_u32(np, "reg", &port_no);
if (!rc && port_no == port)
return np;
}
return NULL;
}
static int fsi_i2c_probe(struct device *dev)
{
struct fsi_i2c_master *i2c;
struct fsi_i2c_port *port;
struct device_node *np;
u32 port_no, ports, stat;
int rc;
i2c = devm_kzalloc(dev, sizeof(*i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
mutex_init(&i2c->lock);
i2c->fsi = to_fsi_dev(dev);
INIT_LIST_HEAD(&i2c->ports);
rc = fsi_i2c_dev_init(i2c);
if (rc)
return rc;
rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
if (rc)
return rc;
ports = FIELD_GET(I2C_STAT_MAX_PORT, stat) + 1;
dev_dbg(dev, "I2C master has %d ports\n", ports);
for (port_no = 0; port_no < ports; port_no++) {
np = fsi_i2c_find_port_of_node(dev->of_node, port_no);
if (np && !of_device_is_available(np))
continue;
port = kzalloc(sizeof(*port), GFP_KERNEL);
if (!port) {
of_node_put(np);
break;
}
port->master = i2c;
port->port = port_no;
port->adapter.owner = THIS_MODULE;
port->adapter.dev.of_node = np;
port->adapter.dev.parent = dev;
port->adapter.algo = &fsi_i2c_algorithm;
port->adapter.bus_recovery_info = &fsi_i2c_bus_recovery_info;
port->adapter.algo_data = port;
snprintf(port->adapter.name, sizeof(port->adapter.name),
"i2c_bus-%u", port_no);
rc = i2c_add_adapter(&port->adapter);
if (rc < 0) {
dev_err(dev, "Failed to register adapter: %d\n", rc);
kfree(port);
continue;
}
list_add(&port->list, &i2c->ports);
}
dev_set_drvdata(dev, i2c);
return 0;
}
static int fsi_i2c_remove(struct device *dev)
{
struct fsi_i2c_master *i2c = dev_get_drvdata(dev);
struct fsi_i2c_port *port, *tmp;
list_for_each_entry_safe(port, tmp, &i2c->ports, list) {
list_del(&port->list);
i2c_del_adapter(&port->adapter);
kfree(port);
}
return 0;
}
static const struct fsi_device_id fsi_i2c_ids[] = {
{ FSI_ENGID_I2C, FSI_VERSION_ANY },
{ }
};
static struct fsi_driver fsi_i2c_driver = {
.id_table = fsi_i2c_ids,
.drv = {
.name = "i2c-fsi",
.bus = &fsi_bus_type,
.probe = fsi_i2c_probe,
.remove = fsi_i2c_remove,
},
};
module_fsi_driver(fsi_i2c_driver);
MODULE_AUTHOR("Eddie James <eajames@us.ibm.com>");
MODULE_DESCRIPTION("FSI attached I2C master");
MODULE_LICENSE("GPL");