blob: 46fb6c42934f227ebf5151d37e3f23c0ee10ee10 [file] [log] [blame]
/*
* (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/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
/* Controller command patterns */
#define SW_TWSI_V BIT_ULL(63) /* Valid bit */
#define SW_TWSI_R BIT_ULL(56) /* Result or read bit */
/* Controller opcode word (bits 60:57) */
#define SW_TWSI_OP_SHIFT 57
#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
#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 */
/* Some status values */
#define STAT_START 0x08
#define STAT_RSTART 0x10
#define STAT_TXADDR_ACK 0x18
#define STAT_TXDATA_ACK 0x28
#define STAT_RXADDR_ACK 0x40
#define STAT_RXDATA_ACK 0x50
#define STAT_IDLE 0xF8
/* TWSI_INT values */
#define TWSI_INT_CORE_EN BIT_ULL(6)
#define TWSI_INT_SDA_OVR BIT_ULL(8)
#define TWSI_INT_SCL_OVR BIT_ULL(9)
struct octeon_i2c {
wait_queue_head_t queue;
struct i2c_adapter adap;
int irq;
u32 twsi_freq;
int sys_freq;
void __iomem *twsi_base;
struct device *dev;
};
/**
* octeon_i2c_write_sw - 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_write_sw(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);
}
/**
* octeon_i2c_read_sw - 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_read_sw(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;
}
/**
* 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)
{
__raw_writeq(data, i2c->twsi_base + TWSI_INT);
__raw_readq(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_unblock - unblock the bus
* @i2c: The struct octeon_i2c
*
* If there was a reset while a device was driving 0 to bus, bus is blocked.
* We toggle it free manually by some clock cycles and send a stop.
*/
static void octeon_i2c_unblock(struct octeon_i2c *i2c)
{
int i;
dev_dbg(i2c->dev, "%s\n", __func__);
for (i = 0; i < 9; i++) {
octeon_i2c_write_int(i2c, 0);
udelay(5);
octeon_i2c_write_int(i2c, TWSI_INT_SCL_OVR);
udelay(5);
}
/* hand-crank a STOP */
octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR | TWSI_INT_SCL_OVR);
udelay(5);
octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR);
udelay(5);
octeon_i2c_write_int(i2c, 0);
}
/* interrupt service routine */
static irqreturn_t octeon_i2c_isr(int irq, void *dev_id)
{
struct octeon_i2c *i2c = dev_id;
octeon_i2c_int_disable(i2c);
wake_up(&i2c->queue);
return IRQ_HANDLED;
}
static int octeon_i2c_test_iflg(struct octeon_i2c *i2c)
{
return (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_CTL) & TWSI_CTL_IFLG) != 0;
}
/**
* 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;
octeon_i2c_int_enable(i2c);
time_left = wait_event_timeout(i2c->queue, octeon_i2c_test_iflg(i2c),
i2c->adap.timeout);
octeon_i2c_int_disable(i2c);
if (!time_left) {
dev_dbg(i2c->dev, "%s: timeout\n", __func__);
return -ETIMEDOUT;
}
return 0;
}
/**
* 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 result;
u8 data;
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
TWSI_CTL_ENAB | TWSI_CTL_STA);
result = octeon_i2c_wait(i2c);
if (result) {
if (octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT) == STAT_IDLE) {
/*
* Controller refused to send start flag May
* be a client is holding SDA low - let's try
* to free it.
*/
octeon_i2c_unblock(i2c);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
TWSI_CTL_ENAB | TWSI_CTL_STA);
result = octeon_i2c_wait(i2c);
}
if (result)
return result;
}
data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
if ((data != STAT_START) && (data != STAT_RSTART)) {
dev_err(i2c->dev, "%s: bad status (0x%x)\n", __func__, data);
return -EIO;
}
return 0;
}
/* send STOP to the bus */
static void octeon_i2c_stop(struct octeon_i2c *i2c)
{
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
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;
u8 tmp;
result = octeon_i2c_start(i2c);
if (result)
return result;
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, target << 1);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
for (i = 0; i < length; i++) {
tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
if ((tmp != STAT_TXADDR_ACK) && (tmp != STAT_TXDATA_ACK)) {
dev_err(i2c->dev,
"%s: bad status before write (0x%x)\n",
__func__, tmp);
return -EIO;
}
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, data[i]);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, 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;
u8 tmp;
if (length < 1)
return -EINVAL;
result = octeon_i2c_start(i2c);
if (result)
return result;
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, (target << 1) | 1);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
for (i = 0; i < length; i++) {
tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
if ((tmp != STAT_RXDATA_ACK) && (tmp != STAT_RXADDR_ACK)) {
dev_err(i2c->dev,
"%s: bad status before read (0x%x)\n",
__func__, tmp);
return -EIO;
}
if (i + 1 < length)
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
TWSI_CTL_ENAB | TWSI_CTL_AAK);
else
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
TWSI_CTL_ENAB);
result = octeon_i2c_wait(i2c);
if (result)
return result;
data[i] = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_DATA);
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];
}
}
*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;
for (i = 0; ret == 0 && i < num; i++) {
struct i2c_msg *pmsg = &msgs[i];
dev_dbg(i2c->dev,
"Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
pmsg->flags & I2C_M_RD ? "read" : "write",
pmsg->len, pmsg->addr, i + 1, num);
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);
return (ret != 0) ? ret : num;
}
static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
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,
.timeout = HZ / 50,
};
/* 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_write_sw(i2c, SW_TWSI_OP_TWSI_CLK, thp);
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CLKCTL, (mdiv << 3) | ndiv);
}
static int octeon_i2c_init_lowlevel(struct octeon_i2c *i2c)
{
u8 status;
int tries;
/* disable high level controller, enable bus access */
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
/* reset controller */
octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_RST, 0);
for (tries = 10; tries; tries--) {
udelay(1);
status = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
if (status == STAT_IDLE)
return 0;
}
dev_err(i2c->dev, "%s: TWSI_RST failed! (0x%x)\n", __func__, status);
return -EIO;
}
static int octeon_i2c_probe(struct platform_device *pdev)
{
struct device_node *node = pdev->dev.of_node;
struct resource *res_mem;
struct octeon_i2c *i2c;
int irq, result = 0;
/* 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;
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.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", },
{},
};
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");