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Message-ID: <ZxJqITunljv0PGxn@ryzen.lan>
Date: Fri, 18 Oct 2024 16:01:05 +0200
From: Niklas Cassel <cassel@...nel.org>
To: Frank Li <Frank.Li@....com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
Krzysztof WilczyĆski <kw@...ux.com>,
Kishon Vijay Abraham I <kishon@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>, Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
imx@...ts.linux.dev, dlemoal@...nel.org, maz@...nel.org,
tglx@...utronix.de, jdmason@...zu.us
Subject: Re: [PATCH v3 4/6] PCI: endpoint: pci-epf-test: Add doorbell test
support
Hello Frank,
On Tue, Oct 15, 2024 at 06:07:17PM -0400, Frank Li wrote:
> Add three registers: doorbell_bar, doorbell_addr, and doorbell_data,
> along with doorbell_done. Use pci_epf_alloc_doorbell() to allocate a
> doorbell address space.
>
> Enable the Root Complex (RC) side driver to trigger pci-epc-test's doorbell
> callback handler by writing doorbell_data to the mapped doorbell_bar's
> address space.
>
> Set doorbell_done in the doorbell callback to indicate completion.
>
> To avoid broken compatibility, use new PID/VID and set RevID bigger than 0.
> So only new pcitest program can distinguish with/without doorbell support
> and avoid wrongly write test data to doorbell bar.
>
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> drivers/pci/endpoint/functions/pci-epf-test.c | 58 ++++++++++++++++++++++++++-
> 1 file changed, 56 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 7c2ed6eae53ad..c054d621353a6 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -11,12 +11,14 @@
> #include <linux/dmaengine.h>
> #include <linux/io.h>
> #include <linux/module.h>
> +#include <linux/msi.h>
> #include <linux/slab.h>
> #include <linux/pci_ids.h>
> #include <linux/random.h>
>
> #include <linux/pci-epc.h>
> #include <linux/pci-epf.h>
> +#include <linux/pci-ep-msi.h>
> #include <linux/pci_regs.h>
>
> #define IRQ_TYPE_INTX 0
> @@ -39,6 +41,7 @@
> #define STATUS_IRQ_RAISED BIT(6)
> #define STATUS_SRC_ADDR_INVALID BIT(7)
> #define STATUS_DST_ADDR_INVALID BIT(8)
> +#define STATUS_DOORBELL_SUCCESS BIT(9)
>
> #define FLAG_USE_DMA BIT(0)
>
> @@ -50,6 +53,7 @@ struct pci_epf_test {
> void *reg[PCI_STD_NUM_BARS];
> struct pci_epf *epf;
> enum pci_barno test_reg_bar;
> + enum pci_barno doorbell_bar;
> size_t msix_table_offset;
> struct delayed_work cmd_handler;
> struct dma_chan *dma_chan_tx;
> @@ -74,6 +78,9 @@ struct pci_epf_test_reg {
> u32 irq_type;
> u32 irq_number;
> u32 flags;
> + u32 doorbell_bar;
> + u32 doorbell_addr;
> + u32 doorbell_data;
> } __packed;
>
> static struct pci_epf_header test_header = {
> @@ -695,7 +702,7 @@ static int pci_epf_test_set_bar(struct pci_epf *epf)
> enum pci_barno test_reg_bar = epf_test->test_reg_bar;
>
> for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> - if (!epf_test->reg[bar])
> + if (!epf_test->reg[bar] && bar != epf_test->doorbell_bar)
> continue;
>
> ret = pci_epc_set_bar(epc, epf->func_no, epf->vfunc_no,
> @@ -810,11 +817,24 @@ static int pci_epf_test_link_down(struct pci_epf *epf)
> return 0;
> }
>
> +static int pci_epf_test_doorbell(struct pci_epf *epf, int index)
> +{
> + struct pci_epf_test *epf_test = epf_get_drvdata(epf);
> + enum pci_barno test_reg_bar = epf_test->test_reg_bar;
> + struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
> +
> + reg->status |= STATUS_DOORBELL_SUCCESS;
> + pci_epf_test_raise_irq(epf_test, reg);
> +
> + return 0;
> +}
> +
> static const struct pci_epc_event_ops pci_epf_test_event_ops = {
> .epc_init = pci_epf_test_epc_init,
> .epc_deinit = pci_epf_test_epc_deinit,
> .link_up = pci_epf_test_link_up,
> .link_down = pci_epf_test_link_down,
> + .doorbell = pci_epf_test_doorbell,
> };
>
> static int pci_epf_test_alloc_space(struct pci_epf *epf)
> @@ -853,7 +873,7 @@ static int pci_epf_test_alloc_space(struct pci_epf *epf)
> if (bar == NO_BAR)
> break;
>
> - if (bar == test_reg_bar)
> + if (bar == test_reg_bar || bar == epf_test->doorbell_bar)
> continue;
>
> base = pci_epf_alloc_space(epf, bar_size[bar], bar,
> @@ -887,7 +907,11 @@ static int pci_epf_test_bind(struct pci_epf *epf)
> struct pci_epf_test *epf_test = epf_get_drvdata(epf);
> const struct pci_epc_features *epc_features;
> enum pci_barno test_reg_bar = BAR_0;
> + enum pci_barno doorbell_bar = NO_BAR;
> struct pci_epc *epc = epf->epc;
> + struct msi_msg *msg;
> + u64 doorbell_addr;
> + u32 align;
>
> if (WARN_ON_ONCE(!epc))
> return -EINVAL;
> @@ -905,10 +929,40 @@ static int pci_epf_test_bind(struct pci_epf *epf)
> epf_test->test_reg_bar = test_reg_bar;
> epf_test->epc_features = epc_features;
>
> + align = epc_features->align;
> + align = align ? align : 128;
> +
> + /* Only revid >=1 support RC-to-EP Door bell */
> + ret = epf->header->revid > 0 ? pci_epf_alloc_doorbell(epf, 1) : -EINVAL;
I really, really don't like this idea.
This means that you would need to write a revid > 1 in configfs to test this.
I also don't think that it is right that pci-epf-test takes ownership of "rev".
How about something like this instead:
My thinking is that you add a doorbell_capable struct member to epc_features,
and then populate CAPS_DOORBELL_SUPPORT based on epc_features in
pci_epf_test_init_caps() (similar to how my proposal sets CAPS_MSI_SUPPORT).
>From 0f6bb535c6d56e03e9b3550194deec04a1c1d370 Mon Sep 17 00:00:00 2001
From: Niklas Cassel <cassel@...nel.org>
Date: Fri, 18 Oct 2024 10:32:39 +0200
Subject: [PATCH] PCI: endpoint: pci-epf-test: Add support for exposing EPC
capabilities
Currently, there is no way for the pci-endpoint-test driver (RC side),
to know which features the EPC supports.
Expose some of the EPC:s capabilities in the test_reg_bar, such that
the pci-endpoint-test driver can know if a feature (e.g. MSI-X or DMA)
is supported before attempting to test it.
Signed-off-by: Niklas Cassel <cassel@...nel.org>
---
drivers/misc/pci_endpoint_test.c | 34 +++++++++++++++
drivers/pci/endpoint/functions/pci-epf-test.c | 43 +++++++++++++++++++
2 files changed, 77 insertions(+)
diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
index 3aaaf47fa4ee..7eb045dc81b6 100644
--- a/drivers/misc/pci_endpoint_test.c
+++ b/drivers/misc/pci_endpoint_test.c
@@ -69,6 +69,20 @@
#define PCI_ENDPOINT_TEST_FLAGS 0x2c
#define FLAG_USE_DMA BIT(0)
+#define CAPS_MAGIC 0x25ccf687
+#define PCI_ENDPOINT_TEST_CAPS_MAGIC 0x30
+#define PCI_ENDPOINT_TEST_CAPS_VERSION 0x34
+#define PCI_ENDPOINT_TEST_CAPS 0x38
+
+#define CAPS_MSI_SUPPORT BIT(0)
+#define CAPS_MSIX_SUPPORT BIT(1)
+#define CAPS_DMA_SUPPORT BIT(2)
+#define CAPS_DMA_IS_PRIVATE BIT(3) /* only valid if DMA_SUPPORT */
+#define CAPS_DOORBELL_SUPPORT BIT(4)
+#define CAPS_DOORBELL_BAR_MASK GENMASK(7, 5) /* only valid if DOORBELL_SUPPORT */
+#define CAPS_DOORBELL_BAR_SHIFT 5
+#define CAPS_DOORBELL_BAR(x) (((x) & CAPS_DOORBELL_BAR_MASK) >> CAPS_DOORBELL_BAR_SHIFT)
+
#define PCI_DEVICE_ID_TI_AM654 0xb00c
#define PCI_DEVICE_ID_TI_J7200 0xb00f
#define PCI_DEVICE_ID_TI_AM64 0xb010
@@ -805,6 +819,24 @@ static const struct file_operations pci_endpoint_test_fops = {
.unlocked_ioctl = pci_endpoint_test_ioctl,
};
+static void pci_endpoint_get_caps(struct pci_endpoint_test *test)
+{
+ u32 caps_magic, caps;
+
+ /* check if endpoint has CAPS support */
+ caps_magic = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_CAPS_MAGIC);
+ if (caps_magic != CAPS_MAGIC)
+ return;
+
+ caps = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_CAPS);
+ pr_info("CAPS: MSI support: %u\n", (caps & CAPS_MSI_SUPPORT) ? 1 : 0);
+ pr_info("CAPS: MSI-X support: %u\n", (caps & CAPS_MSIX_SUPPORT) ? 1 : 0);
+ pr_info("CAPS: DMA support: %u\n", (caps & CAPS_DMA_SUPPORT) ? 1 : 0);
+ pr_info("CAPS: DMA is private: %u\n", (caps & CAPS_DMA_IS_PRIVATE) ? 1 : 0);
+ pr_info("CAPS: DOORBELL support: %u\n", (caps & CAPS_DOORBELL_SUPPORT) ? 1 : 0);
+ pr_info("CAPS: DOORBELL BAR: %lu\n", CAPS_DOORBELL_BAR(caps));
+}
+
static int pci_endpoint_test_probe(struct pci_dev *pdev,
const struct pci_device_id *ent)
{
@@ -906,6 +938,8 @@ static int pci_endpoint_test_probe(struct pci_dev *pdev,
goto err_kfree_test_name;
}
+ pci_endpoint_get_caps(test);
+
misc_device = &test->miscdev;
misc_device->minor = MISC_DYNAMIC_MINOR;
misc_device->name = kstrdup(name, GFP_KERNEL);
diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index a73bc0771d35..2dd90e2e8565 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -44,6 +44,18 @@
#define TIMER_RESOLUTION 1
+#define CAPS_MAGIC 0x25ccf687
+#define CAPS_VERSION 0x1
+
+#define CAPS_MSI_SUPPORT BIT(0)
+#define CAPS_MSIX_SUPPORT BIT(1)
+#define CAPS_DMA_SUPPORT BIT(2)
+#define CAPS_DMA_IS_PRIVATE BIT(3) /* only valid if DMA_SUPPORT */
+#define CAPS_DOORBELL_SUPPORT BIT(4)
+#define CAPS_DOORBELL_BAR_MASK GENMASK(7, 5) /* only valid if DOORBELL_SUPPORT */
+#define CAPS_DOORBELL_BAR_SHIFT 5
+#define CAPS_DOORBELL_BAR(x) (((x) & CAPS_DOORBELL_BAR_MASK) >> CAPS_DOORBELL_BAR_SHIFT)
+
static struct workqueue_struct *kpcitest_workqueue;
struct pci_epf_test {
@@ -74,6 +86,9 @@ struct pci_epf_test_reg {
u32 irq_type;
u32 irq_number;
u32 flags;
+ u32 caps_magic;
+ u32 caps_version;
+ u32 caps;
} __packed;
static struct pci_epf_header test_header = {
@@ -741,6 +756,32 @@ static void pci_epf_test_clear_bar(struct pci_epf *epf)
}
}
+static void pci_epf_test_init_caps(struct pci_epf *epf)
+{
+ struct pci_epf_test *epf_test = epf_get_drvdata(epf);
+ const struct pci_epc_features *epc_features = epf_test->epc_features;
+ enum pci_barno test_reg_bar = epf_test->test_reg_bar;
+ struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
+ u32 caps = 0;
+
+ reg->caps_magic = cpu_to_le32(CAPS_MAGIC);
+ reg->caps_version = cpu_to_le32(CAPS_VERSION);
+
+ if (epc_features->msi_capable)
+ caps |= CAPS_MSI_SUPPORT;
+
+ if (epc_features->msix_capable)
+ caps |= CAPS_MSIX_SUPPORT;
+
+ if (epf_test->dma_supported)
+ caps |= CAPS_DMA_SUPPORT;
+
+ if (epf_test->dma_private)
+ caps |= CAPS_DMA_IS_PRIVATE;
+
+ reg->caps = cpu_to_le64(caps);
+}
+
static int pci_epf_test_epc_init(struct pci_epf *epf)
{
struct pci_epf_test *epf_test = epf_get_drvdata(epf);
@@ -765,6 +806,8 @@ static int pci_epf_test_epc_init(struct pci_epf *epf)
}
}
+ pci_epf_test_init_caps(epf);
+
ret = pci_epf_test_set_bar(epf);
if (ret)
return ret;
--
2.47.0
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