[PATCH] drivers/misc: add Aspeed LPC snoop driver
Rob Lippert
rlippert at google.com
Tue Jun 6 05:46:20 AEST 2017
On Sun, Jun 4, 2017 at 8:25 PM, Joel Stanley <joel at jms.id.au> wrote:
> 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/).
What is the proper upstream mailing list for this? patman didn't list
any mailing lists...
The aspeed-lpc-ctrl that I used as a reference has no bindings in
upstream, was that intentional or oversight?
-Rob
>
> 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
>>
More information about the openbmc
mailing list