On 2/26/24 7:13 AM, Basavaraj Natikar wrote:
> AMD MP2 STB function provides a data buffer used to log debug information
> about the system execution during S2Idle suspend/resume.
>
> A data buffer known as the STB (Smart Trace Buffer) is a circular buffer
> which is a low-level log to assist in debugging by providing insights
> into any potential hangs or stalls that may occur during the S2Idle
> suspend/resume processes.
>
> The current PMC driver retrieves STB data from MP1, but there can be
> scenarios where MP1 might hang or become unresponsive, leading to the
> loss of critical data present in the STB buffer. This defeats the purpose
> of the STB buffer, which was originally meant to help identify system
> failures.
>
> This feature creates stb_read_previous_boot debugfs allows users to
> retrieve the STB log from MP2 specifically from the last occurrence of
> the S2Idle suspend/resume. A userspace daemon can access STB log of last
> S2Idle suspend/resume which can help to troubleshoot potential issues
> related to hangs or stalls during the S2Idle suspend/resume sequence.
>
> Reviewed-by: Shyam Sundar S K <Shyam-sundar.S-k@xxxxxxx>
> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@xxxxxxx>
> ---
> Changes in v2:
> - Used linux/sizes.h instead of defining KB.
> - Defined timeout containing unit as per USEC_PER_MSEC.
> - Modified macro of AMD_C2P_MSG and AMD_P2C_MSG.
> - Changed string stb to STB in log messages.
> - Defined literals using Macro.
>
> drivers/platform/x86/amd/pmc/Kconfig | 23 +++
> drivers/platform/x86/amd/pmc/Makefile | 1 +
> drivers/platform/x86/amd/pmc/mp2_stb.c | 227 +++++++++++++++++++++++++
> drivers/platform/x86/amd/pmc/pmc.c | 5 +
> drivers/platform/x86/amd/pmc/pmc.h | 12 ++
> 5 files changed, 268 insertions(+)
> create mode 100644 drivers/platform/x86/amd/pmc/mp2_stb.c
>
> diff --git a/drivers/platform/x86/amd/pmc/Kconfig b/drivers/platform/x86/amd/pmc/Kconfig
> index 883c0a95ac0c..8177486babf9 100644
> --- a/drivers/platform/x86/amd/pmc/Kconfig
> +++ b/drivers/platform/x86/amd/pmc/Kconfig
> @@ -18,3 +18,26 @@ config AMD_PMC
>
> If you choose to compile this driver as a module the module will be
> called amd-pmc.
> +
> +config AMD_MP2_STB
> + bool "AMD SoC MP2 STB function"
> + depends on AMD_PMC
> + help
> + AMD MP2 STB function provides a data buffer used to log debug
> + information about the system execution during S2Idle suspend/resume.
> + A data buffer known as the STB (Smart Trace Buffer) is a circular
> + buffer which is a low-level log for the SoC which is used to debug
> + any hangs/stalls during S2Idle suspend/resume.
> +
> + The current PMC driver retrieves STB data from MP1, but there can be
> + scenarios where MP1 might hang or become unresponsive, leading to the
> + loss of critical data present in the STB buffer. This defeats the
> + purpose of the STB buffer, which was originally meant to help identify
> + system failures.
> +
> + Creates stb_read_previous_boot debugfs to get STB, a userspace daemon
> + can access STB log of last S2Idle suspend/resume which can help to
> + debug if hangs/stalls during S2Idle suspend/resume
> +
> + Say Y or N here if you have a notebook powered by AMD RYZEN CPU/APU
> + and supports MP2 STB.
> diff --git a/drivers/platform/x86/amd/pmc/Makefile b/drivers/platform/x86/amd/pmc/Makefile
> index 4aaa29d351c9..f1d9ab19d24c 100644
> --- a/drivers/platform/x86/amd/pmc/Makefile
> +++ b/drivers/platform/x86/amd/pmc/Makefile
> @@ -6,3 +6,4 @@
>
> amd-pmc-objs := pmc.o pmc-quirks.o
> obj-$(CONFIG_AMD_PMC) += amd-pmc.o
> +amd-pmc-$(CONFIG_AMD_MP2_STB) += mp2_stb.o
> diff --git a/drivers/platform/x86/amd/pmc/mp2_stb.c b/drivers/platform/x86/amd/pmc/mp2_stb.c
> new file mode 100644
> index 000000000000..258de76cddce
> --- /dev/null
> +++ b/drivers/platform/x86/amd/pmc/mp2_stb.c
> @@ -0,0 +1,227 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * AMD MP2 STB layer
> + *
> + * Copyright (c) 2024, Advanced Micro Devices, Inc.
> + * All Rights Reserved.
> + *
> + * Author: Basavaraj Natikar <Basavaraj.Natikar@xxxxxxx>
> + */
> +
> +#include <linux/debugfs.h>
> +#include <linux/iopoll.h>
> +#include <linux/pci.h>
> +#include <linux/sizes.h>
> +
> +#include "pmc.h"
> +
> +#define VALID_MSG 0xA
> +#define VALID_RESPONSE 2
> +
> +#define AMD_C2P_MSG0 0x10500
> +#define AMD_C2P_MSG1 0x10504
> +#define AMD_P2C_MSG0 0x10680
> +#define AMD_P2C_MSG1 0x10684
> +
> +#define SLEEP_US (0.5 * USEC_PER_MSEC)
> +#define TIMEOUT_US (1600 * USEC_PER_MSEC)
> +
> +#define LEN_2KB_BIT 1
> +#define LEN_16KB_BIT 4
> +
> +static struct amd_mp2_dev *mp2;
> +
> +struct mp2_cmd_base {
> + union {
> + u32 ul;
> + struct {
> + u32 cmd_id : 4;
> + u32 intr_disable : 1;
> + u32 dma_addr : 1;
> + u32 rsvd : 26;
> + } cmd;
> + };
> +};
> +
> +struct mp2_cmd_response {
> + union {
> + u32 resp;
> + struct {
> + u32 cmd_id : 4;
> + u32 status : 4;
> + u32 response : 4;
> + u32 rsvd2 : 20;
> + } response;
> + };
> +};
> +
> +struct mp2_stb_data_valid {
> + union {
> + u32 data_valid;
> + struct {
> + u32 valid : 16;
> + u32 length : 16;
> + } val;
> + };
> +};
> +
> +static int amd_mp2_wait_response(u8 cmd_id, u32 command_sts)
> +{
> + struct mp2_cmd_response cmd_resp;
> +
> + if (!readl_poll_timeout(mp2->mmio + AMD_P2C_MSG0, cmd_resp.resp,
> + (cmd_resp.response.response == 0x0 &&
> + cmd_resp.response.status == command_sts &&
> + cmd_resp.response.cmd_id == cmd_id), SLEEP_US, TIMEOUT_US))
> + return cmd_resp.response.status;
> +
> + return -ETIMEDOUT;
> +}
> +
> +static void amd_mp2_stb_send_cmd(u8 cmd_id, uint8_t da)
> +{
> + struct mp2_cmd_base cmd_base;
> +
> + cmd_base.ul = 0;
> + cmd_base.cmd.cmd_id = cmd_id;
> + cmd_base.cmd.intr_disable = 1;
> + cmd_base.cmd.dma_addr = da;
> +
> + writeq(mp2->dma_addr, mp2->mmio + AMD_C2P_MSG1);
> + writel(cmd_base.ul, mp2->mmio + AMD_C2P_MSG0);
> +}
> +
> +static int amd_mp2_stb_region(int len)
> +{
> + struct device *dev = &mp2->pdev->dev;
> +
> + len *= SZ_1K;
> +
> + if (!mp2->stbdata) {
> + mp2->vslbase = dmam_alloc_coherent(dev, len, &mp2->dma_addr, GFP_KERNEL);
> + if (!mp2->vslbase)
> + return -ENOMEM;
> +
I don't see you freeing this memory. Don't you need to free it?
> + mp2->stbdata = devm_kzalloc(dev, len, GFP_KERNEL);
> + if (!mp2->stbdata)
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static int amd_mp2_process_cmd(struct file *filp)
> +{
> + struct mp2_stb_data_valid stb_dv;
> + int status, rc;
> +
> + stb_dv.data_valid = readl(mp2->mmio + AMD_P2C_MSG1);
> +
> + if (stb_dv.val.valid != VALID_MSG) {
> + dev_err(&mp2->pdev->dev, "Invalid STB data\n");
> + return -EBADMSG;
> + }
> +
> + if (stb_dv.val.length != LEN_2KB_BIT && stb_dv.val.length != LEN_16KB_BIT) {
> + dev_err(&mp2->pdev->dev, "Unsupported length\n");
> + return -EMSGSIZE;
> + }
> +
> + mp2->stb_len = BIT(stb_dv.val.length);
> +
> + rc = amd_mp2_stb_region(mp2->stb_len);
> + if (rc) {
> + dev_err(&mp2->pdev->dev, "Failed to init STB region, rc %d\n", rc);
> + return rc;
> + }
> +
> + amd_mp2_stb_send_cmd(VALID_MSG, true);
> + status = amd_mp2_wait_response(VALID_MSG, VALID_RESPONSE);
> + if (status == VALID_RESPONSE) {
> + memcpy_fromio(mp2->stbdata, mp2->vslbase, SZ_1K * mp2->stb_len);
> + filp->private_data = mp2->stbdata;
> + mp2->is_stb_data = true;
> + } else {
> + dev_err(&mp2->pdev->dev, "Failed to start STB dump, status %d\n", status);
> + return -EOPNOTSUPP;
> + }
> +
> + return 0;
> +}
> +
> +static int amd_mp2_stb_debugfs_open(struct inode *inode, struct file *filp)
> +{
> + if (!mp2->is_stb_data)
> + return amd_mp2_process_cmd(filp);
> +
> + filp->private_data = mp2->stbdata;
> +
> + return 0;
> +}
> +
> +static ssize_t amd_mp2_stb_debugfs_read(struct file *filp, char __user *buf, size_t size,
> + loff_t *pos)
> +{
> + if (!filp->private_data)
> + return -EINVAL;
> +
> + return simple_read_from_buffer(buf, size, pos, filp->private_data, SZ_1K * mp2->stb_len);
> +}
> +
> +static const struct file_operations amd_mp2_stb_debugfs_fops = {
> + .owner = THIS_MODULE,
> + .open = amd_mp2_stb_debugfs_open,
> + .read = amd_mp2_stb_debugfs_read,
> +};
> +
> +static void amd_mp2_dbgfs_register(struct amd_pmc_dev *dev)
> +{
> + if (!dev->dbgfs_dir)
> + return;
> +
> + debugfs_create_file("stb_read_previous_boot", 0644, dev->dbgfs_dir, dev,
> + &amd_mp2_stb_debugfs_fops);
> +}
> +
> +int amd_mp2_stb_init(struct amd_pmc_dev *dev)
> +{
> + struct pci_dev *pdev;
> + int rc;
> +
> + pdev = pci_get_device(PCI_VENDOR_ID_AMD, 0x172c, NULL);
> + if (!pdev)
> + return -ENODEV;
> +
> + mp2 = devm_kzalloc(dev->dev, sizeof(*mp2), GFP_KERNEL);
> + if (!mp2)
missing pci_dev_put(pdev) here. I recommend doing it at the end with
goto for error paths.
> + return -ENOMEM;
> +
> + mp2->pdev = pdev;
> +
> + rc = pcim_enable_device(pdev);
> + if (rc) {
> + pci_dev_put(pdev);
> + return rc;
> + }
> +
> + rc = pcim_iomap_regions(pdev, BIT(2), "mp2 stb");
> + if (rc) {
> + pci_dev_put(pdev);
Wondering whether you need to disable pci_device?
> + return rc;
> + }
> +
> + /* MP2 MMIO is mapped to BAR2 */
> + mp2->mmio = pcim_iomap_table(pdev)[2];
> + pci_set_master(pdev);
> + rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
> + if (rc) {
> + dev_err(&pdev->dev, "failed to set DMA mask\n");
> + pci_dev_put(pdev);
> + return rc;
> + }
> +
> + amd_mp2_dbgfs_register(dev);
> + dev->mp2 = mp2;
> +
> + return 0;
> +}
> diff --git a/drivers/platform/x86/amd/pmc/pmc.c b/drivers/platform/x86/amd/pmc/pmc.c
> index 108e12fd580f..8baab1c3cca9 100644
> --- a/drivers/platform/x86/amd/pmc/pmc.c
> +++ b/drivers/platform/x86/amd/pmc/pmc.c
> @@ -1106,6 +1106,8 @@ static int amd_pmc_probe(struct platform_device *pdev)
> }
>
> amd_pmc_dbgfs_register(dev);
> + if (IS_ENABLED(CONFIG_AMD_MP2_STB))
> + amd_mp2_stb_init(dev);
> pm_report_max_hw_sleep(U64_MAX);
> return 0;
>
> @@ -1122,6 +1124,9 @@ static void amd_pmc_remove(struct platform_device *pdev)
> acpi_unregister_lps0_dev(&amd_pmc_s2idle_dev_ops);
> amd_pmc_dbgfs_unregister(dev);
> pci_dev_put(dev->rdev);
> + if (IS_ENABLED(CONFIG_AMD_MP2_STB))
> + if (dev->mp2 && dev->mp2->pdev)
> + pci_dev_put(dev->mp2->pdev);
> mutex_destroy(&dev->lock);
> }
>
> diff --git a/drivers/platform/x86/amd/pmc/pmc.h b/drivers/platform/x86/amd/pmc/pmc.h
> index 827eef65e133..be0f6b674133 100644
> --- a/drivers/platform/x86/amd/pmc/pmc.h
> +++ b/drivers/platform/x86/amd/pmc/pmc.h
> @@ -14,6 +14,16 @@
> #include <linux/types.h>
> #include <linux/mutex.h>
>
> +struct amd_mp2_dev {
> + void __iomem *mmio;
> + void __iomem *vslbase;
> + void *stbdata;
> + struct pci_dev *pdev;
> + dma_addr_t dma_addr;
> + int stb_len;
> + bool is_stb_data;
> +};
> +
> struct amd_pmc_dev {
> void __iomem *regbase;
> void __iomem *smu_virt_addr;
> @@ -38,10 +48,12 @@ struct amd_pmc_dev {
> struct dentry *dbgfs_dir;
> struct quirk_entry *quirks;
> bool disable_8042_wakeup;
> + struct amd_mp2_dev *mp2;
> };
>
> void amd_pmc_process_restore_quirks(struct amd_pmc_dev *dev);
> void amd_pmc_quirks_init(struct amd_pmc_dev *dev);
> +int amd_mp2_stb_init(struct amd_pmc_dev *dev);
>
> /* List of supported CPU ids */
> #define AMD_CPU_ID_RV 0x15D0
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
