tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright 2017 Google Inc
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *
9 * Provides a simple driver to control the ASPEED LPC snoop interface which
10 * allows the BMC to listen on and save the data written by
11 * the host to an arbitrary LPC I/O port.
12 *
13 * Typically used by the BMC to "watch" host boot progress via port
14 * 0x80 writes made by the BIOS during the boot process.
15 */
16
17#include <linux/bitops.h>
18#include <linux/interrupt.h>
19#include <linux/kfifo.h>
20#include <linux/mfd/syscon.h>
21#include <linux/module.h>
22#include <linux/of.h>
23#include <linux/of_device.h>
24#include <linux/platform_device.h>
25#include <linux/regmap.h>
26
27#define DEVICE_NAME "aspeed-lpc-snoop"
28
29#define NUM_SNOOP_CHANNELS 2
30#define SNOOP_FIFO_SIZE 2048
31
32#define HICR5 0x0
33#define HICR5_EN_SNP0W BIT(0)
34#define HICR5_ENINT_SNP0W BIT(1)
35#define HICR5_EN_SNP1W BIT(2)
36#define HICR5_ENINT_SNP1W BIT(3)
37
38#define HICR6 0x4
39#define HICR6_STR_SNP0W BIT(0)
40#define HICR6_STR_SNP1W BIT(1)
41#define SNPWADR 0x10
42#define SNPWADR_CH0_MASK GENMASK(15, 0)
43#define SNPWADR_CH0_SHIFT 0
44#define SNPWADR_CH1_MASK GENMASK(31, 16)
45#define SNPWADR_CH1_SHIFT 16
46#define SNPWDR 0x14
47#define SNPWDR_CH0_MASK GENMASK(7, 0)
48#define SNPWDR_CH0_SHIFT 0
49#define SNPWDR_CH1_MASK GENMASK(15, 8)
50#define SNPWDR_CH1_SHIFT 8
51#define HICRB 0x80
52#define HICRB_ENSNP0D BIT(14)
53#define HICRB_ENSNP1D BIT(15)
54
55struct aspeed_lpc_snoop_model_data {
56 /* The ast2400 has bits 14 and 15 as reserved, whereas the ast2500
57 * can use them.
58 */
59 unsigned int has_hicrb_ensnp;
60};
61
62struct aspeed_lpc_snoop {
63 struct regmap *regmap;
64 int irq;
65 struct kfifo snoop_fifo[NUM_SNOOP_CHANNELS];
66};
67
68/* Save a byte to a FIFO and discard the oldest byte if FIFO is full */
69static void put_fifo_with_discard(struct kfifo *fifo, u8 val)
70{
71 if (!kfifo_initialized(fifo))
72 return;
73 if (kfifo_is_full(fifo))
74 kfifo_skip(fifo);
75 kfifo_put(fifo, val);
76}
77
78static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg)
79{
80 struct aspeed_lpc_snoop *lpc_snoop = arg;
81 u32 reg, data;
82
83 if (regmap_read(lpc_snoop->regmap, HICR6, ®))
84 return IRQ_NONE;
85
86 /* Check if one of the snoop channels is interrupting */
87 reg &= (HICR6_STR_SNP0W | HICR6_STR_SNP1W);
88 if (!reg)
89 return IRQ_NONE;
90
91 /* Ack pending IRQs */
92 regmap_write(lpc_snoop->regmap, HICR6, reg);
93
94 /* Read and save most recent snoop'ed data byte to FIFO */
95 regmap_read(lpc_snoop->regmap, SNPWDR, &data);
96
97 if (reg & HICR6_STR_SNP0W) {
98 u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT;
99
100 put_fifo_with_discard(&lpc_snoop->snoop_fifo[0], val);
101 }
102 if (reg & HICR6_STR_SNP1W) {
103 u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT;
104
105 put_fifo_with_discard(&lpc_snoop->snoop_fifo[1], val);
106 }
107
108 return IRQ_HANDLED;
109}
110
111static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop,
112 struct platform_device *pdev)
113{
114 struct device *dev = &pdev->dev;
115 int rc;
116
117 lpc_snoop->irq = platform_get_irq(pdev, 0);
118 if (!lpc_snoop->irq)
119 return -ENODEV;
120
121 rc = devm_request_irq(dev, lpc_snoop->irq,
122 aspeed_lpc_snoop_irq, IRQF_SHARED,
123 DEVICE_NAME, lpc_snoop);
124 if (rc < 0) {
125 dev_warn(dev, "Unable to request IRQ %d\n", lpc_snoop->irq);
126 lpc_snoop->irq = 0;
127 return rc;
128 }
129
130 return 0;
131}
132
133static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
134 struct device *dev,
135 int channel, u16 lpc_port)
136{
137 int rc = 0;
138 u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en;
139 const struct aspeed_lpc_snoop_model_data *model_data =
140 of_device_get_match_data(dev);
141
142 /* Create FIFO datastructure */
143 rc = kfifo_alloc(&lpc_snoop->snoop_fifo[channel],
144 SNOOP_FIFO_SIZE, GFP_KERNEL);
145 if (rc)
146 return rc;
147
148 /* Enable LPC snoop channel at requested port */
149 switch (channel) {
150 case 0:
151 hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W;
152 snpwadr_mask = SNPWADR_CH0_MASK;
153 snpwadr_shift = SNPWADR_CH0_SHIFT;
154 hicrb_en = HICRB_ENSNP0D;
155 break;
156 case 1:
157 hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W;
158 snpwadr_mask = SNPWADR_CH1_MASK;
159 snpwadr_shift = SNPWADR_CH1_SHIFT;
160 hicrb_en = HICRB_ENSNP1D;
161 break;
162 default:
163 return -EINVAL;
164 }
165
166 regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);
167 regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask,
168 lpc_port << snpwadr_shift);
169 if (model_data->has_hicrb_ensnp)
170 regmap_update_bits(lpc_snoop->regmap, HICRB,
171 hicrb_en, hicrb_en);
172
173 return rc;
174}
175
176static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
177 int channel)
178{
179 switch (channel) {
180 case 0:
181 regmap_update_bits(lpc_snoop->regmap, HICR5,
182 HICR5_EN_SNP0W | HICR5_ENINT_SNP0W,
183 0);
184 break;
185 case 1:
186 regmap_update_bits(lpc_snoop->regmap, HICR5,
187 HICR5_EN_SNP1W | HICR5_ENINT_SNP1W,
188 0);
189 break;
190 default:
191 return;
192 }
193
194 kfifo_free(&lpc_snoop->snoop_fifo[channel]);
195}
196
197static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
198{
199 struct aspeed_lpc_snoop *lpc_snoop;
200 struct device *dev;
201 u32 port;
202 int rc;
203
204 dev = &pdev->dev;
205
206 lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL);
207 if (!lpc_snoop)
208 return -ENOMEM;
209
210 lpc_snoop->regmap = syscon_node_to_regmap(
211 pdev->dev.parent->of_node);
212 if (IS_ERR(lpc_snoop->regmap)) {
213 dev_err(dev, "Couldn't get regmap\n");
214 return -ENODEV;
215 }
216
217 dev_set_drvdata(&pdev->dev, lpc_snoop);
218
219 rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port);
220 if (rc) {
221 dev_err(dev, "no snoop ports configured\n");
222 return -ENODEV;
223 }
224
225 rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev);
226 if (rc)
227 return rc;
228
229 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 0, port);
230 if (rc)
231 return rc;
232
233 /* Configuration of 2nd snoop channel port is optional */
234 if (of_property_read_u32_index(dev->of_node, "snoop-ports",
235 1, &port) == 0) {
236 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 1, port);
237 if (rc)
238 aspeed_lpc_disable_snoop(lpc_snoop, 0);
239 }
240
241 return rc;
242}
243
244static int aspeed_lpc_snoop_remove(struct platform_device *pdev)
245{
246 struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev);
247
248 /* Disable both snoop channels */
249 aspeed_lpc_disable_snoop(lpc_snoop, 0);
250 aspeed_lpc_disable_snoop(lpc_snoop, 1);
251
252 return 0;
253}
254
255static const struct aspeed_lpc_snoop_model_data ast2400_model_data = {
256 .has_hicrb_ensnp = 0,
257};
258
259static const struct aspeed_lpc_snoop_model_data ast2500_model_data = {
260 .has_hicrb_ensnp = 1,
261};
262
263static const struct of_device_id aspeed_lpc_snoop_match[] = {
264 { .compatible = "aspeed,ast2400-lpc-snoop",
265 .data = &ast2400_model_data },
266 { .compatible = "aspeed,ast2500-lpc-snoop",
267 .data = &ast2500_model_data },
268 { },
269};
270
271static struct platform_driver aspeed_lpc_snoop_driver = {
272 .driver = {
273 .name = DEVICE_NAME,
274 .of_match_table = aspeed_lpc_snoop_match,
275 },
276 .probe = aspeed_lpc_snoop_probe,
277 .remove = aspeed_lpc_snoop_remove,
278};
279
280module_platform_driver(aspeed_lpc_snoop_driver);
281
282MODULE_DEVICE_TABLE(of, aspeed_lpc_snoop_match);
283MODULE_LICENSE("GPL");
284MODULE_AUTHOR("Robert Lippert <rlippert@google.com>");
285MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality");