--- /dev/null
+/*
+ * 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");
projects / mirror_ubuntu-bionic-kernel.git / commitdiff