diff options
Diffstat (limited to 'drivers/misc/aspeed-lpc-snoop.c')
| -rw-r--r-- | drivers/misc/aspeed-lpc-snoop.c | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/drivers/misc/aspeed-lpc-snoop.c b/drivers/misc/aspeed-lpc-snoop.c new file mode 100644 index 000000000000..593905565b74 --- /dev/null +++ b/drivers/misc/aspeed-lpc-snoop.c @@ -0,0 +1,261 @@ +/* + * Copyright 2017 Google Inc + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + * 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/interrupt.h> +#include <linux/kfifo.h> +#include <linux/mfd/syscon.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/regmap.h> + +#define DEVICE_NAME "aspeed-lpc-snoop" + +#define NUM_SNOOP_CHANNELS 2 +#define SNOOP_FIFO_SIZE 2048 + +#define HICR5 0x0 +#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 0x4 +#define HICR6_STR_SNP0W BIT(0) +#define HICR6_STR_SNP1W BIT(1) +#define SNPWADR 0x10 +#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 0x14 +#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 0x80 +#define HICRB_ENSNP0D BIT(14) +#define HICRB_ENSNP1D BIT(15) + +struct aspeed_lpc_snoop { + struct regmap *regmap; + int irq; + struct kfifo snoop_fifo[NUM_SNOOP_CHANNELS]; +}; + +/* Save a byte to a FIFO and discard the oldest byte if FIFO is full */ +static void put_fifo_with_discard(struct kfifo *fifo, u8 val) +{ + if (!kfifo_initialized(fifo)) + return; + if (kfifo_is_full(fifo)) + kfifo_skip(fifo); + kfifo_put(fifo, val); +} + +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->snoop_fifo[0], val); + } + if (reg & HICR6_STR_SNP1W) { + u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT; + + put_fifo_with_discard(&lpc_snoop->snoop_fifo[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) + 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; +} + +static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop, + int channel, u16 lpc_port) +{ + int rc = 0; + u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en; + + /* Create FIFO datastructure */ + rc = kfifo_alloc(&lpc_snoop->snoop_fifo[channel], + SNOOP_FIFO_SIZE, GFP_KERNEL); + if (rc) + return rc; + + /* Enable LPC snoop channel at requested port */ + switch (channel) { + case 0: + hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W; + snpwadr_mask = SNPWADR_CH0_MASK; + snpwadr_shift = SNPWADR_CH0_SHIFT; + hicrb_en = HICRB_ENSNP0D; + break; + case 1: + hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W; + snpwadr_mask = SNPWADR_CH1_MASK; + snpwadr_shift = SNPWADR_CH1_SHIFT; + hicrb_en = HICRB_ENSNP1D; + break; + default: + return -EINVAL; + } + + regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en); + regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask, + lpc_port << snpwadr_shift); + regmap_update_bits(lpc_snoop->regmap, HICRB, hicrb_en, hicrb_en); + + return rc; +} + +static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop, + int channel) +{ + switch (channel) { + case 0: + regmap_update_bits(lpc_snoop->regmap, HICR5, + HICR5_EN_SNP0W | HICR5_ENINT_SNP0W, + 0); + break; + case 1: + regmap_update_bits(lpc_snoop->regmap, HICR5, + HICR5_EN_SNP1W | HICR5_ENINT_SNP1W, + 0); + break; + default: + return; + } + + kfifo_free(&lpc_snoop->snoop_fifo[channel]); +} + +static int aspeed_lpc_snoop_probe(struct platform_device *pdev) +{ + struct aspeed_lpc_snoop *lpc_snoop; + struct device *dev; + u32 port; + int rc; + + dev = &pdev->dev; + + lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL); + if (!lpc_snoop) + return -ENOMEM; + + lpc_snoop->regmap = syscon_node_to_regmap( + pdev->dev.parent->of_node); + if (IS_ERR(lpc_snoop->regmap)) { + dev_err(dev, "Couldn't get regmap\n"); + return -ENODEV; + } + + dev_set_drvdata(&pdev->dev, lpc_snoop); + + rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port); + if (rc) { + dev_err(dev, "no snoop ports configured\n"); + return -ENODEV; + } + + rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev); + if (rc) + return rc; + + rc = aspeed_lpc_enable_snoop(lpc_snoop, 0, port); + if (rc) + return rc; + + /* Configuration of 2nd snoop channel port is optional */ + if (of_property_read_u32_index(dev->of_node, "snoop-ports", + 1, &port) == 0) { + rc = aspeed_lpc_enable_snoop(lpc_snoop, 1, port); + if (rc) + aspeed_lpc_disable_snoop(lpc_snoop, 0); + } + + return rc; +} + +static int 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, 0); + aspeed_lpc_disable_snoop(lpc_snoop, 1); + + return 0; +} + +static const struct of_device_id aspeed_lpc_snoop_match[] = { + { .compatible = "aspeed,ast2500-lpc-snoop" }, + { }, +}; + +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"); |
