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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Copyright 2017 Google Inc4 *5 * Provides a simple driver to control the ASPEED LPC snoop interface which6 * allows the BMC to listen on and save the data written by7 * the host to an arbitrary LPC I/O port.8 *9 * Typically used by the BMC to "watch" host boot progress via port10 * 0x80 writes made by the BIOS during the boot process.11 */12 13#include <linux/bitops.h>14#include <linux/clk.h>15#include <linux/interrupt.h>16#include <linux/fs.h>17#include <linux/kfifo.h>18#include <linux/mfd/syscon.h>19#include <linux/miscdevice.h>20#include <linux/module.h>21#include <linux/of.h>22#include <linux/platform_device.h>23#include <linux/poll.h>24#include <linux/regmap.h>25 26#define DEVICE_NAME "aspeed-lpc-snoop"27 28#define NUM_SNOOP_CHANNELS 229#define SNOOP_FIFO_SIZE 204830 31#define HICR5 0x8032#define HICR5_EN_SNP0W BIT(0)33#define HICR5_ENINT_SNP0W BIT(1)34#define HICR5_EN_SNP1W BIT(2)35#define HICR5_ENINT_SNP1W BIT(3)36#define HICR6 0x8437#define HICR6_STR_SNP0W BIT(0)38#define HICR6_STR_SNP1W BIT(1)39#define SNPWADR 0x9040#define SNPWADR_CH0_MASK GENMASK(15, 0)41#define SNPWADR_CH0_SHIFT 042#define SNPWADR_CH1_MASK GENMASK(31, 16)43#define SNPWADR_CH1_SHIFT 1644#define SNPWDR 0x9445#define SNPWDR_CH0_MASK GENMASK(7, 0)46#define SNPWDR_CH0_SHIFT 047#define SNPWDR_CH1_MASK GENMASK(15, 8)48#define SNPWDR_CH1_SHIFT 849#define HICRB 0x10050#define HICRB_ENSNP0D BIT(14)51#define HICRB_ENSNP1D BIT(15)52 53struct aspeed_lpc_snoop_model_data {54 /* The ast2400 has bits 14 and 15 as reserved, whereas the ast250055 * can use them.56 */57 unsigned int has_hicrb_ensnp;58};59 60struct aspeed_lpc_snoop_channel {61 struct kfifo fifo;62 wait_queue_head_t wq;63 struct miscdevice miscdev;64};65 66struct aspeed_lpc_snoop {67 struct regmap *regmap;68 int irq;69 struct clk *clk;70 struct aspeed_lpc_snoop_channel chan[NUM_SNOOP_CHANNELS];71};72 73static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file)74{75 return container_of(file->private_data,76 struct aspeed_lpc_snoop_channel,77 miscdev);78}79 80static ssize_t snoop_file_read(struct file *file, char __user *buffer,81 size_t count, loff_t *ppos)82{83 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file);84 unsigned int copied;85 int ret = 0;86 87 if (kfifo_is_empty(&chan->fifo)) {88 if (file->f_flags & O_NONBLOCK)89 return -EAGAIN;90 ret = wait_event_interruptible(chan->wq,91 !kfifo_is_empty(&chan->fifo));92 if (ret == -ERESTARTSYS)93 return -EINTR;94 }95 ret = kfifo_to_user(&chan->fifo, buffer, count, &copied);96 if (ret)97 return ret;98 99 return copied;100}101 102static __poll_t snoop_file_poll(struct file *file,103 struct poll_table_struct *pt)104{105 struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file);106 107 poll_wait(file, &chan->wq, pt);108 return !kfifo_is_empty(&chan->fifo) ? EPOLLIN : 0;109}110 111static const struct file_operations snoop_fops = {112 .owner = THIS_MODULE,113 .read = snoop_file_read,114 .poll = snoop_file_poll,115 .llseek = noop_llseek,116};117 118/* Save a byte to a FIFO and discard the oldest byte if FIFO is full */119static void put_fifo_with_discard(struct aspeed_lpc_snoop_channel *chan, u8 val)120{121 if (!kfifo_initialized(&chan->fifo))122 return;123 if (kfifo_is_full(&chan->fifo))124 kfifo_skip(&chan->fifo);125 kfifo_put(&chan->fifo, val);126 wake_up_interruptible(&chan->wq);127}128 129static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg)130{131 struct aspeed_lpc_snoop *lpc_snoop = arg;132 u32 reg, data;133 134 if (regmap_read(lpc_snoop->regmap, HICR6, ®))135 return IRQ_NONE;136 137 /* Check if one of the snoop channels is interrupting */138 reg &= (HICR6_STR_SNP0W | HICR6_STR_SNP1W);139 if (!reg)140 return IRQ_NONE;141 142 /* Ack pending IRQs */143 regmap_write(lpc_snoop->regmap, HICR6, reg);144 145 /* Read and save most recent snoop'ed data byte to FIFO */146 regmap_read(lpc_snoop->regmap, SNPWDR, &data);147 148 if (reg & HICR6_STR_SNP0W) {149 u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT;150 151 put_fifo_with_discard(&lpc_snoop->chan[0], val);152 }153 if (reg & HICR6_STR_SNP1W) {154 u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT;155 156 put_fifo_with_discard(&lpc_snoop->chan[1], val);157 }158 159 return IRQ_HANDLED;160}161 162static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop,163 struct platform_device *pdev)164{165 struct device *dev = &pdev->dev;166 int rc;167 168 lpc_snoop->irq = platform_get_irq(pdev, 0);169 if (!lpc_snoop->irq)170 return -ENODEV;171 172 rc = devm_request_irq(dev, lpc_snoop->irq,173 aspeed_lpc_snoop_irq, IRQF_SHARED,174 DEVICE_NAME, lpc_snoop);175 if (rc < 0) {176 dev_warn(dev, "Unable to request IRQ %d\n", lpc_snoop->irq);177 lpc_snoop->irq = 0;178 return rc;179 }180 181 return 0;182}183 184static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,185 struct device *dev,186 int channel, u16 lpc_port)187{188 int rc = 0;189 u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en;190 const struct aspeed_lpc_snoop_model_data *model_data =191 of_device_get_match_data(dev);192 193 init_waitqueue_head(&lpc_snoop->chan[channel].wq);194 /* Create FIFO datastructure */195 rc = kfifo_alloc(&lpc_snoop->chan[channel].fifo,196 SNOOP_FIFO_SIZE, GFP_KERNEL);197 if (rc)198 return rc;199 200 lpc_snoop->chan[channel].miscdev.minor = MISC_DYNAMIC_MINOR;201 lpc_snoop->chan[channel].miscdev.name =202 devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, channel);203 lpc_snoop->chan[channel].miscdev.fops = &snoop_fops;204 lpc_snoop->chan[channel].miscdev.parent = dev;205 rc = misc_register(&lpc_snoop->chan[channel].miscdev);206 if (rc)207 return rc;208 209 /* Enable LPC snoop channel at requested port */210 switch (channel) {211 case 0:212 hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W;213 snpwadr_mask = SNPWADR_CH0_MASK;214 snpwadr_shift = SNPWADR_CH0_SHIFT;215 hicrb_en = HICRB_ENSNP0D;216 break;217 case 1:218 hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W;219 snpwadr_mask = SNPWADR_CH1_MASK;220 snpwadr_shift = SNPWADR_CH1_SHIFT;221 hicrb_en = HICRB_ENSNP1D;222 break;223 default:224 return -EINVAL;225 }226 227 regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);228 regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask,229 lpc_port << snpwadr_shift);230 if (model_data->has_hicrb_ensnp)231 regmap_update_bits(lpc_snoop->regmap, HICRB,232 hicrb_en, hicrb_en);233 234 return rc;235}236 237static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,238 int channel)239{240 switch (channel) {241 case 0:242 regmap_update_bits(lpc_snoop->regmap, HICR5,243 HICR5_EN_SNP0W | HICR5_ENINT_SNP0W,244 0);245 break;246 case 1:247 regmap_update_bits(lpc_snoop->regmap, HICR5,248 HICR5_EN_SNP1W | HICR5_ENINT_SNP1W,249 0);250 break;251 default:252 return;253 }254 255 kfifo_free(&lpc_snoop->chan[channel].fifo);256 misc_deregister(&lpc_snoop->chan[channel].miscdev);257}258 259static int aspeed_lpc_snoop_probe(struct platform_device *pdev)260{261 struct aspeed_lpc_snoop *lpc_snoop;262 struct device *dev;263 struct device_node *np;264 u32 port;265 int rc;266 267 dev = &pdev->dev;268 269 lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL);270 if (!lpc_snoop)271 return -ENOMEM;272 273 np = pdev->dev.parent->of_node;274 if (!of_device_is_compatible(np, "aspeed,ast2400-lpc-v2") &&275 !of_device_is_compatible(np, "aspeed,ast2500-lpc-v2") &&276 !of_device_is_compatible(np, "aspeed,ast2600-lpc-v2")) {277 dev_err(dev, "unsupported LPC device binding\n");278 return -ENODEV;279 }280 281 lpc_snoop->regmap = syscon_node_to_regmap(np);282 if (IS_ERR(lpc_snoop->regmap)) {283 dev_err(dev, "Couldn't get regmap\n");284 return -ENODEV;285 }286 287 dev_set_drvdata(&pdev->dev, lpc_snoop);288 289 rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port);290 if (rc) {291 dev_err(dev, "no snoop ports configured\n");292 return -ENODEV;293 }294 295 lpc_snoop->clk = devm_clk_get(dev, NULL);296 if (IS_ERR(lpc_snoop->clk)) {297 rc = PTR_ERR(lpc_snoop->clk);298 if (rc != -EPROBE_DEFER)299 dev_err(dev, "couldn't get clock\n");300 return rc;301 }302 rc = clk_prepare_enable(lpc_snoop->clk);303 if (rc) {304 dev_err(dev, "couldn't enable clock\n");305 return rc;306 }307 308 rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev);309 if (rc)310 goto err;311 312 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 0, port);313 if (rc)314 goto err;315 316 /* Configuration of 2nd snoop channel port is optional */317 if (of_property_read_u32_index(dev->of_node, "snoop-ports",318 1, &port) == 0) {319 rc = aspeed_lpc_enable_snoop(lpc_snoop, dev, 1, port);320 if (rc) {321 aspeed_lpc_disable_snoop(lpc_snoop, 0);322 goto err;323 }324 }325 326 return 0;327 328err:329 clk_disable_unprepare(lpc_snoop->clk);330 331 return rc;332}333 334static void aspeed_lpc_snoop_remove(struct platform_device *pdev)335{336 struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev);337 338 /* Disable both snoop channels */339 aspeed_lpc_disable_snoop(lpc_snoop, 0);340 aspeed_lpc_disable_snoop(lpc_snoop, 1);341 342 clk_disable_unprepare(lpc_snoop->clk);343}344 345static const struct aspeed_lpc_snoop_model_data ast2400_model_data = {346 .has_hicrb_ensnp = 0,347};348 349static const struct aspeed_lpc_snoop_model_data ast2500_model_data = {350 .has_hicrb_ensnp = 1,351};352 353static const struct of_device_id aspeed_lpc_snoop_match[] = {354 { .compatible = "aspeed,ast2400-lpc-snoop",355 .data = &ast2400_model_data },356 { .compatible = "aspeed,ast2500-lpc-snoop",357 .data = &ast2500_model_data },358 { .compatible = "aspeed,ast2600-lpc-snoop",359 .data = &ast2500_model_data },360 { },361};362 363static struct platform_driver aspeed_lpc_snoop_driver = {364 .driver = {365 .name = DEVICE_NAME,366 .of_match_table = aspeed_lpc_snoop_match,367 },368 .probe = aspeed_lpc_snoop_probe,369 .remove_new = aspeed_lpc_snoop_remove,370};371 372module_platform_driver(aspeed_lpc_snoop_driver);373 374MODULE_DEVICE_TABLE(of, aspeed_lpc_snoop_match);375MODULE_LICENSE("GPL");376MODULE_AUTHOR("Robert Lippert <rlippert@google.com>");377MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality");378