diff options
Diffstat (limited to 'drivers/soc/aspeed/aspeed-lpc-snoop.c')
| -rw-r--r-- | drivers/soc/aspeed/aspeed-lpc-snoop.c | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/drivers/soc/aspeed/aspeed-lpc-snoop.c b/drivers/soc/aspeed/aspeed-lpc-snoop.c new file mode 100644 index 000000000000..b03310c0830d --- /dev/null +++ b/drivers/soc/aspeed/aspeed-lpc-snoop.c @@ -0,0 +1,384 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright 2017 Google Inc + * + * Provides a simple driver to control the ASPEED LPC snoop interface which + * allows the BMC to listen on and save the data written by + * the host to an arbitrary LPC I/O port. + * + * Typically used by the BMC to "watch" host boot progress via port + * 0x80 writes made by the BIOS during the boot process. + */ + +#include <linux/bitops.h> +#include <linux/clk.h> +#include <linux/dev_printk.h> +#include <linux/interrupt.h> +#include <linux/fs.h> +#include <linux/kfifo.h> +#include <linux/mfd/syscon.h> +#include <linux/miscdevice.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/poll.h> +#include <linux/regmap.h> + +#define DEVICE_NAME "aspeed-lpc-snoop" + +#define SNOOP_FIFO_SIZE 2048 + +#define HICR5 0x80 +#define HICR5_EN_SNP0W BIT(0) +#define HICR5_ENINT_SNP0W BIT(1) +#define HICR5_EN_SNP1W BIT(2) +#define HICR5_ENINT_SNP1W BIT(3) +#define HICR6 0x84 +#define HICR6_STR_SNP0W BIT(0) +#define HICR6_STR_SNP1W BIT(1) +#define SNPWADR 0x90 +#define SNPWADR_CH0_MASK GENMASK(15, 0) +#define SNPWADR_CH0_SHIFT 0 +#define SNPWADR_CH1_MASK GENMASK(31, 16) +#define SNPWADR_CH1_SHIFT 16 +#define SNPWDR 0x94 +#define SNPWDR_CH0_MASK GENMASK(7, 0) +#define SNPWDR_CH0_SHIFT 0 +#define SNPWDR_CH1_MASK GENMASK(15, 8) +#define SNPWDR_CH1_SHIFT 8 +#define HICRB 0x100 +#define HICRB_ENSNP0D BIT(14) +#define HICRB_ENSNP1D BIT(15) + +struct aspeed_lpc_snoop_model_data { + /* The ast2400 has bits 14 and 15 as reserved, whereas the ast2500 + * can use them. + */ + unsigned int has_hicrb_ensnp; +}; + +enum aspeed_lpc_snoop_index { + ASPEED_LPC_SNOOP_INDEX_0 = 0, + ASPEED_LPC_SNOOP_INDEX_1 = 1, + ASPEED_LPC_SNOOP_INDEX_MAX = ASPEED_LPC_SNOOP_INDEX_1, +}; + +struct aspeed_lpc_snoop_channel_cfg { + enum aspeed_lpc_snoop_index index; + u32 hicr5_en; + u32 snpwadr_mask; + u32 snpwadr_shift; + u32 hicrb_en; +}; + +struct aspeed_lpc_snoop_channel { + const struct aspeed_lpc_snoop_channel_cfg *cfg; + bool enabled; + struct kfifo fifo; + wait_queue_head_t wq; + struct miscdevice miscdev; +}; + +struct aspeed_lpc_snoop { + struct regmap *regmap; + int irq; + struct clk *clk; + struct aspeed_lpc_snoop_channel chan[ASPEED_LPC_SNOOP_INDEX_MAX + 1]; +}; + +static const struct aspeed_lpc_snoop_channel_cfg channel_cfgs[ASPEED_LPC_SNOOP_INDEX_MAX + 1] = { + { + .index = ASPEED_LPC_SNOOP_INDEX_0, + .hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W, + .snpwadr_mask = SNPWADR_CH0_MASK, + .snpwadr_shift = SNPWADR_CH0_SHIFT, + .hicrb_en = HICRB_ENSNP0D, + }, + { + .index = ASPEED_LPC_SNOOP_INDEX_1, + .hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W, + .snpwadr_mask = SNPWADR_CH1_MASK, + .snpwadr_shift = SNPWADR_CH1_SHIFT, + .hicrb_en = HICRB_ENSNP1D, + }, +}; + +static struct aspeed_lpc_snoop_channel *snoop_file_to_chan(struct file *file) +{ + return container_of(file->private_data, + struct aspeed_lpc_snoop_channel, + miscdev); +} + +static ssize_t snoop_file_read(struct file *file, char __user *buffer, + size_t count, loff_t *ppos) +{ + struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file); + unsigned int copied; + int ret = 0; + + if (kfifo_is_empty(&chan->fifo)) { + if (file->f_flags & O_NONBLOCK) + return -EAGAIN; + ret = wait_event_interruptible(chan->wq, + !kfifo_is_empty(&chan->fifo)); + if (ret == -ERESTARTSYS) + return -EINTR; + } + ret = kfifo_to_user(&chan->fifo, buffer, count, &copied); + if (ret) + return ret; + + return copied; +} + +static __poll_t snoop_file_poll(struct file *file, + struct poll_table_struct *pt) +{ + struct aspeed_lpc_snoop_channel *chan = snoop_file_to_chan(file); + + poll_wait(file, &chan->wq, pt); + return !kfifo_is_empty(&chan->fifo) ? EPOLLIN : 0; +} + +static const struct file_operations snoop_fops = { + .owner = THIS_MODULE, + .read = snoop_file_read, + .poll = snoop_file_poll, + .llseek = noop_llseek, +}; + +/* Save a byte to a FIFO and discard the oldest byte if FIFO is full */ +static void put_fifo_with_discard(struct aspeed_lpc_snoop_channel *chan, u8 val) +{ + if (!kfifo_initialized(&chan->fifo)) + return; + if (kfifo_is_full(&chan->fifo)) + kfifo_skip(&chan->fifo); + kfifo_put(&chan->fifo, val); + wake_up_interruptible(&chan->wq); +} + +static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg) +{ + struct aspeed_lpc_snoop *lpc_snoop = arg; + u32 reg, data; + + if (regmap_read(lpc_snoop->regmap, HICR6, ®)) + return IRQ_NONE; + + /* Check if one of the snoop channels is interrupting */ + reg &= (HICR6_STR_SNP0W | HICR6_STR_SNP1W); + if (!reg) + return IRQ_NONE; + + /* Ack pending IRQs */ + regmap_write(lpc_snoop->regmap, HICR6, reg); + + /* Read and save most recent snoop'ed data byte to FIFO */ + regmap_read(lpc_snoop->regmap, SNPWDR, &data); + + if (reg & HICR6_STR_SNP0W) { + u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT; + + put_fifo_with_discard(&lpc_snoop->chan[0], val); + } + if (reg & HICR6_STR_SNP1W) { + u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT; + + put_fifo_with_discard(&lpc_snoop->chan[1], val); + } + + return IRQ_HANDLED; +} + +static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop, + struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + int rc; + + lpc_snoop->irq = platform_get_irq(pdev, 0); + if (lpc_snoop->irq < 0) + return -ENODEV; + + rc = devm_request_irq(dev, lpc_snoop->irq, + aspeed_lpc_snoop_irq, IRQF_SHARED, + DEVICE_NAME, lpc_snoop); + if (rc < 0) { + dev_warn(dev, "Unable to request IRQ %d\n", lpc_snoop->irq); + lpc_snoop->irq = 0; + return rc; + } + + return 0; +} + +__attribute__((nonnull)) +static int aspeed_lpc_enable_snoop(struct device *dev, + struct aspeed_lpc_snoop *lpc_snoop, + struct aspeed_lpc_snoop_channel *channel, + const struct aspeed_lpc_snoop_channel_cfg *cfg, + u16 lpc_port) +{ + const struct aspeed_lpc_snoop_model_data *model_data; + int rc = 0; + + if (WARN_ON(channel->enabled)) + return -EBUSY; + + init_waitqueue_head(&channel->wq); + + channel->cfg = cfg; + channel->miscdev.minor = MISC_DYNAMIC_MINOR; + channel->miscdev.fops = &snoop_fops; + channel->miscdev.parent = dev; + + channel->miscdev.name = + devm_kasprintf(dev, GFP_KERNEL, "%s%d", DEVICE_NAME, cfg->index); + if (!channel->miscdev.name) + return -ENOMEM; + + rc = kfifo_alloc(&channel->fifo, SNOOP_FIFO_SIZE, GFP_KERNEL); + if (rc) + return rc; + + rc = misc_register(&channel->miscdev); + if (rc) + goto err_free_fifo; + + /* Enable LPC snoop channel at requested port */ + regmap_set_bits(lpc_snoop->regmap, HICR5, cfg->hicr5_en); + regmap_update_bits(lpc_snoop->regmap, SNPWADR, cfg->snpwadr_mask, + lpc_port << cfg->snpwadr_shift); + + model_data = of_device_get_match_data(dev); + if (model_data && model_data->has_hicrb_ensnp) + regmap_set_bits(lpc_snoop->regmap, HICRB, cfg->hicrb_en); + + channel->enabled = true; + + return 0; + +err_free_fifo: + kfifo_free(&channel->fifo); + return rc; +} + +__attribute__((nonnull)) +static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop, + struct aspeed_lpc_snoop_channel *channel) +{ + if (!channel->enabled) + return; + + /* Disable interrupts along with the device */ + regmap_clear_bits(lpc_snoop->regmap, HICR5, channel->cfg->hicr5_en); + + channel->enabled = false; + /* Consider improving safety wrt concurrent reader(s) */ + misc_deregister(&channel->miscdev); + kfifo_free(&channel->fifo); +} + +static void aspeed_lpc_snoop_remove(struct platform_device *pdev) +{ + struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev); + + /* Disable both snoop channels */ + aspeed_lpc_disable_snoop(lpc_snoop, &lpc_snoop->chan[0]); + aspeed_lpc_disable_snoop(lpc_snoop, &lpc_snoop->chan[1]); +} + +static int aspeed_lpc_snoop_probe(struct platform_device *pdev) +{ + struct aspeed_lpc_snoop *lpc_snoop; + struct device_node *np; + struct device *dev; + int idx; + int rc; + + dev = &pdev->dev; + + lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL); + if (!lpc_snoop) + return -ENOMEM; + + np = pdev->dev.parent->of_node; + if (!of_device_is_compatible(np, "aspeed,ast2400-lpc-v2") && + !of_device_is_compatible(np, "aspeed,ast2500-lpc-v2") && + !of_device_is_compatible(np, "aspeed,ast2600-lpc-v2")) { + dev_err(dev, "unsupported LPC device binding\n"); + return -ENODEV; + } + + lpc_snoop->regmap = syscon_node_to_regmap(np); + if (IS_ERR(lpc_snoop->regmap)) + return dev_err_probe(dev, PTR_ERR(lpc_snoop->regmap), "Couldn't get regmap\n"); + + dev_set_drvdata(&pdev->dev, lpc_snoop); + + lpc_snoop->clk = devm_clk_get_enabled(dev, NULL); + if (IS_ERR(lpc_snoop->clk)) + return dev_err_probe(dev, PTR_ERR(lpc_snoop->clk), "couldn't get clock"); + + rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev); + if (rc) + return rc; + + static_assert(ARRAY_SIZE(channel_cfgs) == ARRAY_SIZE(lpc_snoop->chan), + "Broken implementation assumption regarding cfg count"); + for (idx = ASPEED_LPC_SNOOP_INDEX_0; idx <= ASPEED_LPC_SNOOP_INDEX_MAX; idx++) { + u32 port; + + rc = of_property_read_u32_index(dev->of_node, "snoop-ports", idx, &port); + if (rc) + break; + + rc = aspeed_lpc_enable_snoop(dev, lpc_snoop, &lpc_snoop->chan[idx], + &channel_cfgs[idx], port); + if (rc) + goto cleanup_channels; + } + + return idx == ASPEED_LPC_SNOOP_INDEX_0 ? -ENODEV : 0; + +cleanup_channels: + aspeed_lpc_snoop_remove(pdev); + + return rc; +} + +static const struct aspeed_lpc_snoop_model_data ast2400_model_data = { + .has_hicrb_ensnp = 0, +}; + +static const struct aspeed_lpc_snoop_model_data ast2500_model_data = { + .has_hicrb_ensnp = 1, +}; + +static const struct of_device_id aspeed_lpc_snoop_match[] = { + { .compatible = "aspeed,ast2400-lpc-snoop", + .data = &ast2400_model_data }, + { .compatible = "aspeed,ast2500-lpc-snoop", + .data = &ast2500_model_data }, + { .compatible = "aspeed,ast2600-lpc-snoop", + .data = &ast2500_model_data }, + { }, +}; + +static struct platform_driver aspeed_lpc_snoop_driver = { + .driver = { + .name = DEVICE_NAME, + .of_match_table = aspeed_lpc_snoop_match, + }, + .probe = aspeed_lpc_snoop_probe, + .remove = aspeed_lpc_snoop_remove, +}; + +module_platform_driver(aspeed_lpc_snoop_driver); + +MODULE_DEVICE_TABLE(of, aspeed_lpc_snoop_match); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Robert Lippert <rlippert@google.com>"); +MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality"); |