Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
Pull i2c fixes from Wolfram Sang:
"i2c has a bugfix and documentation improvements for you"
* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
Documentation: i2c: mention ACPI method for instantiating devices
Documentation: i2c: describe devicetree method for instantiating devices
i2c: mv64xxx: refactor message start to ensure proper initialization
+53
-21
+39
-2
Documentation/i2c/instantiating-devices
+39
-2
Documentation/i2c/instantiating-devices
···
8
8
several ways to achieve this, depending on the context and requirements.
9
9
10
10
11
-
Method 1: Declare the I2C devices by bus number
12
-
-----------------------------------------------
11
+
Method 1a: Declare the I2C devices by bus number
12
+
------------------------------------------------
13
13
14
14
This method is appropriate when the I2C bus is a system bus as is the case
15
15
for many embedded systems. On such systems, each I2C bus has a number
···
49
49
50
50
The devices will be automatically unbound and destroyed when the I2C bus
51
51
they sit on goes away (if ever.)
52
+
53
+
54
+
Method 1b: Declare the I2C devices via devicetree
55
+
-------------------------------------------------
56
+
57
+
This method has the same implications as method 1a. The declaration of I2C
58
+
devices is here done via devicetree as subnodes of the master controller.
59
+
60
+
Example:
61
+
62
+
i2c1: i2c@400a0000 {
63
+
/* ... master properties skipped ... */
64
+
clock-frequency = <100000>;
65
+
66
+
flash@50 {
67
+
compatible = "atmel,24c256";
68
+
reg = <0x50>;
69
+
};
70
+
71
+
pca9532: gpio@60 {
72
+
compatible = "nxp,pca9532";
73
+
gpio-controller;
74
+
#gpio-cells = <2>;
75
+
reg = <0x60>;
76
+
};
77
+
};
78
+
79
+
Here, two devices are attached to the bus using a speed of 100kHz. For
80
+
additional properties which might be needed to set up the device, please refer
81
+
to its devicetree documentation in Documentation/devicetree/bindings/.
82
+
83
+
84
+
Method 1c: Declare the I2C devices via ACPI
85
+
-------------------------------------------
86
+
87
+
ACPI can also describe I2C devices. There is special documentation for this
88
+
which is currently located at Documentation/acpi/enumeration.txt.
52
89
53
90
54
91
Method 2: Instantiate the devices explicitly
+14
-19
drivers/i2c/busses/i2c-mv64xxx.c
+14
-19
drivers/i2c/busses/i2c-mv64xxx.c
···
97
97
enum {
98
98
MV64XXX_I2C_ACTION_INVALID,
99
99
MV64XXX_I2C_ACTION_CONTINUE,
100
-
MV64XXX_I2C_ACTION_OFFLOAD_SEND_START,
101
100
MV64XXX_I2C_ACTION_SEND_START,
102
101
MV64XXX_I2C_ACTION_SEND_RESTART,
103
102
MV64XXX_I2C_ACTION_OFFLOAD_RESTART,
···
202
203
unsigned long data_reg_lo = 0;
203
204
unsigned long ctrl_reg;
204
205
struct i2c_msg *msg = drv_data->msgs;
206
+
207
+
if (!drv_data->offload_enabled)
208
+
return -EOPNOTSUPP;
205
209
206
210
drv_data->msg = msg;
207
211
drv_data->byte_posn = 0;
···
435
433
436
434
drv_data->msgs++;
437
435
drv_data->num_msgs--;
438
-
if (!(drv_data->offload_enabled &&
439
-
mv64xxx_i2c_offload_msg(drv_data))) {
436
+
if (mv64xxx_i2c_offload_msg(drv_data) < 0) {
440
437
drv_data->cntl_bits |= MV64XXX_I2C_REG_CONTROL_START;
441
438
writel(drv_data->cntl_bits,
442
439
drv_data->reg_base + drv_data->reg_offsets.control);
···
459
458
drv_data->reg_base + drv_data->reg_offsets.control);
460
459
break;
461
460
462
-
case MV64XXX_I2C_ACTION_OFFLOAD_SEND_START:
463
-
if (!mv64xxx_i2c_offload_msg(drv_data))
464
-
break;
465
-
else
466
-
drv_data->action = MV64XXX_I2C_ACTION_SEND_START;
467
-
/* FALLTHRU */
468
461
case MV64XXX_I2C_ACTION_SEND_START:
469
-
writel(drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_START,
470
-
drv_data->reg_base + drv_data->reg_offsets.control);
462
+
/* Can we offload this msg ? */
463
+
if (mv64xxx_i2c_offload_msg(drv_data) < 0) {
464
+
/* No, switch to standard path */
465
+
mv64xxx_i2c_prepare_for_io(drv_data, drv_data->msgs);
466
+
writel(drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_START,
467
+
drv_data->reg_base + drv_data->reg_offsets.control);
468
+
}
471
469
break;
472
470
473
471
case MV64XXX_I2C_ACTION_SEND_ADDR_1:
···
625
625
unsigned long flags;
626
626
627
627
spin_lock_irqsave(&drv_data->lock, flags);
628
-
if (drv_data->offload_enabled) {
629
-
drv_data->action = MV64XXX_I2C_ACTION_OFFLOAD_SEND_START;
630
-
drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
631
-
} else {
632
-
mv64xxx_i2c_prepare_for_io(drv_data, msg);
633
628
634
-
drv_data->action = MV64XXX_I2C_ACTION_SEND_START;
635
-
drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
636
-
}
629
+
drv_data->action = MV64XXX_I2C_ACTION_SEND_START;
630
+
drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
631
+
637
632
drv_data->send_stop = is_last;
638
633
drv_data->block = 1;
639
634
mv64xxx_i2c_do_action(drv_data);