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Subject[PATCH v4 3/6] drivers/i2c: Add transfer implementation for FSI algorithm
Date
From: "Edward A. James" <eajames@us.ibm.com>

Execute I2C transfers from the FSI-attached I2C master. Use polling
instead of interrupts as we have no hardware IRQ over FSI.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
drivers/i2c/busses/i2c-fsi.c | 197 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 195 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 4b52147..f86595b 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -13,10 +13,12 @@
#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/of.h>
+#include <linux/sched.h>

#define FSI_ENGID_I2C 0x7

@@ -140,6 +142,7 @@ struct fsi_i2c_port {
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,
@@ -224,17 +227,207 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
return rc;
}

+static int fsi_i2c_start(struct fsi_i2c_port *port, struct i2c_msg *msg,
+ bool stop)
+{
+ int rc;
+ 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 = SETFIELD(I2C_CMD_ADDR, cmd, msg->addr >> 1);
+ cmd = SETFIELD(I2C_CMD_LEN, cmd, msg->len);
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_CMD, &cmd);
+
+ return rc;
+}
+
+static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
+ u8 fifo_count)
+{
+ int write;
+ int rc = 0;
+ struct fsi_i2c_master *i2c = port->master;
+ int bytes_to_write = i2c->fifo_size - fifo_count;
+ int bytes_remaining = msg->len - port->xfrd;
+
+ if (bytes_to_write > bytes_remaining)
+ bytes_to_write = bytes_remaining;
+
+ while (bytes_to_write > 0) {
+ write = bytes_to_write;
+ /* fsi limited to max 4 byte aligned ops */
+ if (bytes_to_write > 4)
+ write = 4;
+ else if (write == 3)
+ write = 2;
+
+ 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 rc;
+}
+
+static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
+ u8 fifo_count)
+{
+ int read;
+ int rc = 0;
+ struct fsi_i2c_master *i2c = port->master;
+ int xfr_remaining = msg->len - port->xfrd;
+ u32 dummy;
+
+ while (fifo_count) {
+ read = fifo_count;
+ /* fsi limited to max 4 byte aligned ops */
+ if (fifo_count > 4)
+ read = 4;
+ else if (read == 3)
+ read = 2;
+
+ if (xfr_remaining) {
+ if (xfr_remaining < read)
+ read = 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;
+ }
+
+ fifo_count -= read;
+ }
+
+ return rc;
+}
+
+static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
+ struct i2c_msg *msg, u32 status)
+{
+ int rc;
+ u8 fifo_count;
+ struct fsi_i2c_master *i2c = port->master;
+ u32 dummy = 0;
+
+ if (status & I2C_STAT_ERR) {
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+ if (rc)
+ return rc;
+
+ if (status & I2C_STAT_NACK)
+ return -EFAULT;
+
+ return -EIO;
+ }
+
+ if (status & I2C_STAT_DAT_REQ) {
+ fifo_count = GETFIELD(I2C_STAT_FIFO_COUNT, status);
+
+ if (msg->flags & I2C_M_RD)
+ rc = fsi_i2c_read_fifo(port, msg, fifo_count);
+ else
+ rc = fsi_i2c_write_fifo(port, msg, fifo_count);
+
+ return rc;
+ }
+
+ if (status & I2C_STAT_CMD_COMP) {
+ if (port->xfrd < msg->len)
+ rc = -ENODATA;
+ else
+ rc = msg->len;
+
+ return rc;
+ }
+
+ return 0;
+}
+
+static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
+ unsigned long timeout)
+{
+ const unsigned long local_timeout = 2; /* jiffies */
+ u32 status = 0;
+ int rc;
+
+ 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;
+ }
+
+ set_current_state(TASK_UNINTERRUPTIBLE);
+ schedule_timeout(local_timeout);
+ timeout = (timeout < local_timeout) ? 0 :
+ timeout - local_timeout;
+ } while (timeout);
+
+ return -ETIME;
+}
+
static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
- int rc;
+ int i, rc;
+ unsigned long start_time;
struct fsi_i2c_port *port = adap->algo_data;
+ struct i2c_msg *msg;

rc = fsi_i2c_set_port(port);
if (rc)
return rc;

- return -EOPNOTSUPP;
+ for (i = 0; i < num; ++i) {
+ msg = msgs + i;
+ start_time = jiffies;
+
+ rc = fsi_i2c_start(port, msg, i == num - 1);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_wait(port, msg,
+ adap->timeout - (jiffies - start_time));
+ if (rc)
+ return rc;
+ }
+
+ return 0;
}

static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
--
1.8.3.1
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