drivers/misc/aspeed-lpc-snoop.c - kernel/msm-4.19 - Gitiles

 /*
  * 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");
	/*
	* 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");