drivers/misc: add Aspeed LPC snoop driver (9f4f9ae8) · Commits · 戴 / test

drivers/misc/Kconfig

+8 −0

Original line number	Diff line number	Diff line
		@@ -490,6 +490,14 @@ config ASPEED_LPC_CTRL
		ioctl()s, the driver also provides a read/write interface to a BMC ram
		region where the host LPC read/write region can be buffered.

		config ASPEED_LPC_SNOOP
		tristate "Aspeed ast2500 HOST LPC snoop support"
		depends on (ARCH_ASPEED \|\| COMPILE_TEST) && REGMAP && MFD_SYSCON
		help
		Provides a driver to control the 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.

		config PCI_ENDPOINT_TEST
		depends on PCI
		select CRC32

drivers/misc/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -53,6 +53,7 @@ obj-$(CONFIG_ECHO) += echo/
		obj-$(CONFIG_VEXPRESS_SYSCFG) += vexpress-syscfg.o
		obj-$(CONFIG_CXL_BASE) += cxl/
		obj-$(CONFIG_ASPEED_LPC_CTRL) += aspeed-lpc-ctrl.o
		obj-$(CONFIG_ASPEED_LPC_SNOOP) += aspeed-lpc-snoop.o
		obj-$(CONFIG_PCI_ENDPOINT_TEST) += pci_endpoint_test.o

		lkdtm-$(CONFIG_LKDTM) += lkdtm_core.o

drivers/misc/aspeed-lpc-snoop.c

0 → 100644

+261 −0

Original line number	Diff line number	Diff line
		/*
		* 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, &reg))
		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");

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