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Date: Fri, 5 Aug 2011 23:25:12 +0200
From: Tomas <tomasamot@...glemail.com>
To: jim.cromie@...il.com
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 2.6.38 1/1] scx200_acb.c: Add plain i2c (master_xfer / I2C_FUNC_I2C)
From: Tomas Menzl <tomasamot@...il.com>
Add master_xfer / I2C_FUNC_I2C by simply reusing existing FSM
scx200_acb_machine.
This adds possibility to do direct read/write on an i2c device or use
I2C_RDWR ioctl
in addition to existing SM Bus API.
Signed-off-by: Tomas Menzl <tomasamot@...il.com>
----
Added plain I2C interface so that one can use plain read/write (among
others). Needed plain I2C multibyte read which is not possible with SM
bus.
Tested on Voyage Linux 0.75 (http://linux.voyage.hk/, based on Debian
Squeeze, 2.6.38, this module is original/vanilla - i.e. patch
applicable to any current version) on PC Engine WRAP 2C with Microchip
ADC MCP3421.
SM BUS interface intact, read/write worked for me (only tested single
message transactions, do not have HW to test combined transaction but
they are there...).
--- linux-source-2.6.38-voyage/drivers/i2c/busses/scx200_acb.c 2011-08-05
19:44:11.000000000 +0200
+++ linux-source-2.6.38-voyage.new/drivers/i2c/busses/scx200_acb.c 2011-08-05
22:06:18.000000000 +0200
@@ -86,6 +86,7 @@ struct scx200_acb_iface {
u8 *ptr;
char needs_reset;
unsigned len;
+ char skip_stop;
};
/* Register Definitions */
@@ -130,6 +131,7 @@ static void scx200_acb_machine(struct sc
scx200_acb_state_name[iface->state]);
iface->state = state_idle;
+ iface->skip_stop = 0;
iface->result = -ENXIO;
outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
@@ -191,7 +193,8 @@ static void scx200_acb_machine(struct sc
if (iface->len == 1) {
iface->result = 0;
iface->state = state_idle;
- outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
+ if (!iface->skip_stop)
+ outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
}
*iface->ptr++ = inb(ACBSDA);
@@ -203,7 +206,8 @@ static void scx200_acb_machine(struct sc
if (iface->len == 0) {
iface->result = 0;
iface->state = state_idle;
- outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
+ if (!iface->skip_stop)
+ outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
break;
}
@@ -222,6 +226,7 @@ static void scx200_acb_machine(struct sc
iface->len, status);
iface->state = state_idle;
+ iface->skip_stop = 0;
iface->result = -EIO;
iface->needs_reset = 1;
}
@@ -277,6 +282,104 @@ static void scx200_acb_reset(struct scx2
outb(inb(ACBCST) | ACBCST_BB, ACBCST);
}
+/*
+ * Generic i2c master transfer entrypoint.
+ *
+ * Basically copy of part of scx200_acb_smbus_xfer where we use existing
+ * scx200_acb_machine which already supports simple i2c with any data length
+ * (not only 0 and 1 as used by smbus) by using:
+ *
+ * state_quick -> ( state_read | state_write )+ -> state_idle
+ *
+ * Added flag skip_stop to support multimessage ops in scx200_acb_machine
+ * to be able skip stop bit between messages in state_read/state_write:
+ *
+ * S Addr Rd [A] [Data] NA S Addr Wr [A] Data [A] P
+ * ^--- no stop bit! ^--- stop bit
+ *
+ * Still missing 10b address, pec, etc...
+ */
+static int scx200_acb_i2c_master_xfer(struct i2c_adapter *adapter,
+ struct i2c_msg *msgs,
+ int num)
+{
+ struct scx200_acb_iface *iface = i2c_get_adapdata(adapter);
+ int rc = 0;
+ char rw;
+ int len;
+ u8 *buffer;
+ u16 address;
+
+ mutex_lock(&iface->mutex);
+ while (num > 0) {
+ if (msgs->flags & I2C_M_TEN) {
+ dev_err(&adapter->dev,
+ "10b i2c address supported\n");
+ rc = -EINVAL;
+ break;
+ }
+
+ rw = (msgs->flags & I2C_M_RD) != 0;
+ address = (msgs->addr << 1) | rw;
+ len = msgs->len;
+ buffer = msgs->buf;
+
+ dev_dbg(&adapter->dev,
+ "address=0x%x, len=%d, read=%d\n", msgs->addr, len, rw);
+
+ if (!len && rw == I2C_SMBUS_READ) {
+ dev_dbg(&adapter->dev, "zero length read\n");
+ rc = -EINVAL;
+ break;
+ }
+
+ iface->address_byte = address;
+ iface->command = 0;
+ iface->ptr = buffer;
+ iface->len = len;
+ iface->result = -EINVAL;
+ iface->needs_reset = 0;
+ if (num > 1)
+ iface->skip_stop = 1;
+ else
+ iface->skip_stop = 0;
+
+ /* send start */
+ outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);
+
+ /* no command */
+ iface->state = state_quick;
+
+ while (iface->state != state_idle)
+ scx200_acb_poll(iface);
+
+ if (iface->needs_reset)
+ scx200_acb_reset(iface);
+
+ if (iface->result)
+ break;
+
+#ifdef DEBUG
+ dev_dbg(&adapter->dev, "transfer done, result: %d", rc);
+ if (buffer) {
+ int i;
+ printk(KERN_DEBUG " data:");
+ for (i = 0; i < len; ++i)
+ printk(KERN_DEBUG " %02x", buffer[i]);
+ }
+ printk(KERN_DEBUG "\n");
+#endif
+ ++rc;
+ --num;
+ ++msgs;
+ }
+ mutex_unlock(&iface->mutex);
+
+ iface->skip_stop = 0;
+ return rc;
+}
+
+
static s32 scx200_acb_smbus_xfer(struct i2c_adapter *adapter,
u16 address, unsigned short flags,
char rw, u8 command, int size,
@@ -338,6 +441,7 @@ static s32 scx200_acb_smbus_xfer(struct
iface->len = len;
iface->result = -EINVAL;
iface->needs_reset = 0;
+ iface->skip_stop = 0;
outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);
@@ -377,12 +481,13 @@ static u32 scx200_acb_func(struct i2c_ad
{
return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
- I2C_FUNC_SMBUS_I2C_BLOCK;
+ I2C_FUNC_SMBUS_I2C_BLOCK | I2C_FUNC_I2C;
}
/* For now, we only handle combined mode (smbus) */
static const struct i2c_algorithm scx200_acb_algorithm = {
.smbus_xfer = scx200_acb_smbus_xfer,
+ .master_xfer = scx200_acb_i2c_master_xfer,
.functionality = scx200_acb_func,
};
--
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