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@xxxxxxx>
> ---
> 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).
