262 lines
6.4 KiB
C
262 lines
6.4 KiB
C
/*
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* Copyright 2017 Google Inc
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Provides a simple driver to control the ASPEED LPC snoop interface which
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* allows the BMC to listen on and save the data written by
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* the host to an arbitrary LPC I/O port.
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*
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* Typically used by the BMC to "watch" host boot progress via port
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* 0x80 writes made by the BIOS during the boot process.
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*/
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#include <linux/bitops.h>
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#include <linux/interrupt.h>
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#include <linux/kfifo.h>
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#include <linux/mfd/syscon.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/platform_device.h>
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#include <linux/regmap.h>
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#define DEVICE_NAME "aspeed-lpc-snoop"
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#define NUM_SNOOP_CHANNELS 2
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#define SNOOP_FIFO_SIZE 2048
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#define HICR5 0x0
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#define HICR5_EN_SNP0W BIT(0)
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#define HICR5_ENINT_SNP0W BIT(1)
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#define HICR5_EN_SNP1W BIT(2)
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#define HICR5_ENINT_SNP1W BIT(3)
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#define HICR6 0x4
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#define HICR6_STR_SNP0W BIT(0)
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#define HICR6_STR_SNP1W BIT(1)
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#define SNPWADR 0x10
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#define SNPWADR_CH0_MASK GENMASK(15, 0)
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#define SNPWADR_CH0_SHIFT 0
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#define SNPWADR_CH1_MASK GENMASK(31, 16)
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#define SNPWADR_CH1_SHIFT 16
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#define SNPWDR 0x14
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#define SNPWDR_CH0_MASK GENMASK(7, 0)
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#define SNPWDR_CH0_SHIFT 0
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#define SNPWDR_CH1_MASK GENMASK(15, 8)
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#define SNPWDR_CH1_SHIFT 8
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#define HICRB 0x80
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#define HICRB_ENSNP0D BIT(14)
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#define HICRB_ENSNP1D BIT(15)
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struct aspeed_lpc_snoop {
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struct regmap *regmap;
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int irq;
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struct kfifo snoop_fifo[NUM_SNOOP_CHANNELS];
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};
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/* Save a byte to a FIFO and discard the oldest byte if FIFO is full */
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static void put_fifo_with_discard(struct kfifo *fifo, u8 val)
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{
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if (!kfifo_initialized(fifo))
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return;
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if (kfifo_is_full(fifo))
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kfifo_skip(fifo);
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kfifo_put(fifo, val);
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}
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static irqreturn_t aspeed_lpc_snoop_irq(int irq, void *arg)
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{
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struct aspeed_lpc_snoop *lpc_snoop = arg;
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u32 reg, data;
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if (regmap_read(lpc_snoop->regmap, HICR6, ®))
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return IRQ_NONE;
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/* Check if one of the snoop channels is interrupting */
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reg &= (HICR6_STR_SNP0W | HICR6_STR_SNP1W);
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if (!reg)
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return IRQ_NONE;
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/* Ack pending IRQs */
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regmap_write(lpc_snoop->regmap, HICR6, reg);
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/* Read and save most recent snoop'ed data byte to FIFO */
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regmap_read(lpc_snoop->regmap, SNPWDR, &data);
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if (reg & HICR6_STR_SNP0W) {
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u8 val = (data & SNPWDR_CH0_MASK) >> SNPWDR_CH0_SHIFT;
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put_fifo_with_discard(&lpc_snoop->snoop_fifo[0], val);
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}
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if (reg & HICR6_STR_SNP1W) {
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u8 val = (data & SNPWDR_CH1_MASK) >> SNPWDR_CH1_SHIFT;
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put_fifo_with_discard(&lpc_snoop->snoop_fifo[1], val);
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}
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return IRQ_HANDLED;
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}
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static int aspeed_lpc_snoop_config_irq(struct aspeed_lpc_snoop *lpc_snoop,
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struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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int rc;
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lpc_snoop->irq = platform_get_irq(pdev, 0);
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if (!lpc_snoop->irq)
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return -ENODEV;
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rc = devm_request_irq(dev, lpc_snoop->irq,
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aspeed_lpc_snoop_irq, IRQF_SHARED,
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DEVICE_NAME, lpc_snoop);
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if (rc < 0) {
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dev_warn(dev, "Unable to request IRQ %d\n", lpc_snoop->irq);
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lpc_snoop->irq = 0;
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return rc;
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}
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return 0;
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}
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static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
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int channel, u16 lpc_port)
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{
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int rc = 0;
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u32 hicr5_en, snpwadr_mask, snpwadr_shift, hicrb_en;
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/* Create FIFO datastructure */
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rc = kfifo_alloc(&lpc_snoop->snoop_fifo[channel],
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SNOOP_FIFO_SIZE, GFP_KERNEL);
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if (rc)
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return rc;
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/* Enable LPC snoop channel at requested port */
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switch (channel) {
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case 0:
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hicr5_en = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W;
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snpwadr_mask = SNPWADR_CH0_MASK;
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snpwadr_shift = SNPWADR_CH0_SHIFT;
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hicrb_en = HICRB_ENSNP0D;
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break;
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case 1:
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hicr5_en = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W;
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snpwadr_mask = SNPWADR_CH1_MASK;
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snpwadr_shift = SNPWADR_CH1_SHIFT;
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hicrb_en = HICRB_ENSNP1D;
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break;
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default:
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return -EINVAL;
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}
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regmap_update_bits(lpc_snoop->regmap, HICR5, hicr5_en, hicr5_en);
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regmap_update_bits(lpc_snoop->regmap, SNPWADR, snpwadr_mask,
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lpc_port << snpwadr_shift);
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regmap_update_bits(lpc_snoop->regmap, HICRB, hicrb_en, hicrb_en);
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return rc;
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}
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static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
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int channel)
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{
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switch (channel) {
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case 0:
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regmap_update_bits(lpc_snoop->regmap, HICR5,
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HICR5_EN_SNP0W | HICR5_ENINT_SNP0W,
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0);
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break;
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case 1:
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regmap_update_bits(lpc_snoop->regmap, HICR5,
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HICR5_EN_SNP1W | HICR5_ENINT_SNP1W,
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0);
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break;
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default:
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return;
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}
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kfifo_free(&lpc_snoop->snoop_fifo[channel]);
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}
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static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
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{
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struct aspeed_lpc_snoop *lpc_snoop;
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struct device *dev;
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u32 port;
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int rc;
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dev = &pdev->dev;
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lpc_snoop = devm_kzalloc(dev, sizeof(*lpc_snoop), GFP_KERNEL);
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if (!lpc_snoop)
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return -ENOMEM;
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lpc_snoop->regmap = syscon_node_to_regmap(
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pdev->dev.parent->of_node);
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if (IS_ERR(lpc_snoop->regmap)) {
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dev_err(dev, "Couldn't get regmap\n");
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return -ENODEV;
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}
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dev_set_drvdata(&pdev->dev, lpc_snoop);
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rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port);
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if (rc) {
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dev_err(dev, "no snoop ports configured\n");
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return -ENODEV;
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}
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rc = aspeed_lpc_snoop_config_irq(lpc_snoop, pdev);
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if (rc)
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return rc;
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rc = aspeed_lpc_enable_snoop(lpc_snoop, 0, port);
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if (rc)
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return rc;
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/* Configuration of 2nd snoop channel port is optional */
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if (of_property_read_u32_index(dev->of_node, "snoop-ports",
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1, &port) == 0) {
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rc = aspeed_lpc_enable_snoop(lpc_snoop, 1, port);
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if (rc)
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aspeed_lpc_disable_snoop(lpc_snoop, 0);
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}
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return rc;
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}
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static int aspeed_lpc_snoop_remove(struct platform_device *pdev)
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{
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struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev);
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/* Disable both snoop channels */
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aspeed_lpc_disable_snoop(lpc_snoop, 0);
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aspeed_lpc_disable_snoop(lpc_snoop, 1);
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return 0;
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}
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static const struct of_device_id aspeed_lpc_snoop_match[] = {
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{ .compatible = "aspeed,ast2500-lpc-snoop" },
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{ },
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};
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static struct platform_driver aspeed_lpc_snoop_driver = {
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.driver = {
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.name = DEVICE_NAME,
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.of_match_table = aspeed_lpc_snoop_match,
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},
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.probe = aspeed_lpc_snoop_probe,
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.remove = aspeed_lpc_snoop_remove,
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};
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module_platform_driver(aspeed_lpc_snoop_driver);
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MODULE_DEVICE_TABLE(of, aspeed_lpc_snoop_match);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Robert Lippert <rlippert@google.com>");
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MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality");
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