1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
From d100e52bdaef13d3f9aab162719919f660111479 Mon Sep 17 00:00:00 2001
From: Christopher Bostic <cbostic@linux.vnet.ibm.com>
Date: Fri, 17 Mar 2017 16:00:48 -0500
Subject: [PATCH linux dev-4.7 v3] drivers/fsi: Increase delay before sampling
input on SDA
To: joel@jms.id.au
Cc: openbmc@lists.ozlabs.org
During high cpu loads the SDA in line can shift relative to the
clock signal which can corrupt the received input data. Slow
down the time to sample input to account for this.
Add sysfs files to adjust the three main openfsi protocol timing
values: clock delay; sample delay; clock off time.
Signed-off-by: Christopher Bostic <cbostic@linux.vnet.ibm.com>
---
v3 - Add sysfs files to adjust protocol timings
v2 - Increase delay for SDA in sampling only.
- Decrease the original delay for SDA sampling from 1us to 200ns
---
drivers/fsi/fsi-master-gpio.c | 107 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 103 insertions(+), 4 deletions(-)
diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
index a8976d5..0907977 100644
--- a/drivers/fsi/fsi-master-gpio.c
+++ b/drivers/fsi/fsi-master-gpio.c
@@ -14,6 +14,7 @@
#include "fsi-master.h"
#define FSI_GPIO_STD_DLY 1 /* Standard pin delay in nS */
+#define FSI_GPIO_SDA_IN_DLY 200 /* Wait to sample SDA line, in nS */
#define FSI_ECHO_DELAY_CLOCKS 16 /* Number clocks for echo delay */
#define FSI_PRE_BREAK_CLOCKS 50 /* Number clocks to prep for break */
#define FSI_BREAK_CLOCKS 256 /* Number of clocks to issue break */
@@ -65,6 +66,10 @@
static DEFINE_SPINLOCK(fsi_gpio_cmd_lock); /* lock around fsi commands */
+static int clock_delay = FSI_GPIO_STD_DLY;
+static int clock_off_time = FSI_GPIO_STD_DLY;
+static int sample_delay = FSI_GPIO_SDA_IN_DLY;
+
struct fsi_master_gpio {
struct fsi_master master;
struct gpio_desc *gpio_clk;
@@ -86,9 +91,11 @@ static void clock_toggle(struct fsi_master_gpio *master, int count)
int i;
for (i = 0; i < count; i++) {
- ndelay(FSI_GPIO_STD_DLY);
+ udelay(clock_delay / 1000);
+ ndelay(clock_delay % 1000);
gpiod_set_value(master->gpio_clk, 0);
- ndelay(FSI_GPIO_STD_DLY);
+ udelay(clock_off_time / 1000);
+ ndelay(clock_off_time % 1000);
gpiod_set_value(master->gpio_clk, 1);
}
}
@@ -97,7 +104,8 @@ static int sda_in(struct fsi_master_gpio *master)
{
int in;
- ndelay(FSI_GPIO_STD_DLY);
+ udelay(sample_delay / 1000);
+ ndelay(sample_delay % 1000);
in = gpiod_get_value(master->gpio_data);
return in ? 1 : 0;
}
@@ -497,10 +505,77 @@ static ssize_t store_scan(struct device *dev,
static DEVICE_ATTR(scan, 0200, NULL, store_scan);
+static ssize_t clock_delay_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return snprintf(buf, PAGE_SIZE - 1, "%u\n", clock_delay);
+}
+
+static ssize_t clock_delay_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ int rc;
+ unsigned long val = 0;
+
+ rc = kstrtoul(buf, 0, &val);
+ clock_delay = val;
+
+ return count;
+}
+
+DEVICE_ATTR(clock_delay, S_IRUGO | S_IWUSR, clock_delay_show,
+ clock_delay_store);
+
+static ssize_t clock_off_time_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return snprintf(buf, PAGE_SIZE - 1, "%u\n", clock_off_time);
+}
+
+static ssize_t clock_off_time_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ int rc;
+ unsigned long val = 0;
+
+ rc = kstrtoul(buf, 0, &val);
+ clock_off_time = val;
+
+ return count;
+}
+
+DEVICE_ATTR(clock_off_time, S_IRUGO | S_IWUSR, clock_off_time_show,
+ clock_off_time_store);
+
+static ssize_t sample_delay_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return snprintf(buf, PAGE_SIZE - 1, "%u\n", sample_delay);
+}
+
+static ssize_t sample_delay_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ int rc;
+ unsigned long val = 0;
+
+ rc = kstrtoul(buf, 0, &val);
+ sample_delay = val;
+
+ return count;
+}
+
+DEVICE_ATTR(sample_delay, S_IRUGO | S_IWUSR, sample_delay_show,
+ sample_delay_store);
+
static int fsi_master_gpio_probe(struct platform_device *pdev)
{
struct fsi_master_gpio *master;
struct gpio_desc *gpio;
+ int rc;
master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL);
if (!master)
@@ -548,8 +623,29 @@ static int fsi_master_gpio_probe(struct platform_device *pdev)
master->master.send_break = fsi_master_gpio_break;
master->master.link_enable = fsi_master_gpio_link_enable;
platform_set_drvdata(pdev, master);
+ rc = device_create_file(&pdev->dev, &dev_attr_clock_off_time);
+ if (rc)
+ goto done;
+ rc = device_create_file(&pdev->dev, &dev_attr_clock_delay);
+ if (rc)
+ goto rem_clock_off;
+ rc = device_create_file(&pdev->dev, &dev_attr_sample_delay);
+ if (rc)
+ goto rem_clock_delay;
+ rc = device_create_file(&pdev->dev, &dev_attr_scan);
+ if (rc)
+ goto rem_sample_delay;
- return device_create_file(&pdev->dev, &dev_attr_scan);
+ return rc;
+
+rem_sample_delay:
+ device_remove_file(&pdev->dev, &dev_attr_sample_delay);
+rem_clock_delay:
+ device_remove_file(&pdev->dev, &dev_attr_clock_delay);
+rem_clock_off:
+ device_remove_file(&pdev->dev, &dev_attr_clock_off_time);
+done:
+ return rc;
}
@@ -576,6 +672,9 @@ static int fsi_master_gpio_remove(struct platform_device *pdev)
devm_gpiod_put(&pdev->dev, master->gpio_mux);
}
fsi_master_unregister(&master->master);
+ device_remove_file(&pdev->dev, &dev_attr_clock_off_time);
+ device_remove_file(&pdev->dev, &dev_attr_clock_delay);
+ device_remove_file(&pdev->dev, &dev_attr_sample_delay);
device_remove_file(&pdev->dev, &dev_attr_scan);
return 0;
--
1.8.2.2
|
