[PATCH] drivers/misc: add Aspeed LPC snoop driver
Joel Stanley
joel at jms.id.au
Mon Jun 5 13:25:13 AEST 2017
Hello Rob,
On Sat, Jun 3, 2017 at 7:23 AM, Robert Lippert <roblip at gmail.com> wrote:
> This driver enables the LPC snoop hardware on the ASPEED BMC
> which generates an interrupt upon every write to an I/O port
> by the host.
>
> This is typically used to monitor BIOS boot progress by listening
> to well-known debug port 80h.
>
> The functionality in this commit just saves all snooped values
> to a circular 2K buffer in the kernel, subsequent commits can
> act on the values to do things with them.
Reviewed-by: Joel Stanley <joel at jms.id.au>
The driver looks okay to me. I can stage it in the OpenBMC kernel tree
while we get it reviewed upstream.
Can you re-send to the upstream mailing lists so it gets reviewed
there. You will need to include a device tree binding document too
(something to put in Documentation/devicetree/bindings/).
Cheers,
Joel
>
> Signed-off-by: Robert Lippert <rlippert at google.com>
> ---
> drivers/misc/Kconfig | 8 ++
> drivers/misc/Makefile | 1 +
> drivers/misc/aspeed-lpc-snoop.c | 261 ++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 270 insertions(+)
> create mode 100644 drivers/misc/aspeed-lpc-snoop.c
>
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index 07bbd4cc1852..8136dc7e863d 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -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
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index 81ef3e67acc9..b0b766416306 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -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
> 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 at google.com>");
> +MODULE_DESCRIPTION("Linux driver to control Aspeed LPC snoop functionality");
> --
> 2.13.0.506.g27d5fe0cd-goog
>
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