[PATCH v3 4/6] PCI: endpoint: pci-epf-test: Add doorbell test support

[Frank Li]

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;
+	if (!ret) {
+		msg = epf->msg;
+		doorbell_bar = pci_epc_get_next_free_bar(epc_features, test_reg_bar + 1);
+
+		if (doorbell_bar > 0) {
+			epf_test->doorbell_bar = doorbell_bar;
+			doorbell_addr = msg->address_hi;
+			doorbell_addr <<= 32;
+			doorbell_addr |= msg->address_lo;
+			epf->bar[doorbell_bar].phys_addr = round_down(doorbell_addr, align);
+			epf->bar[doorbell_bar].barno = doorbell_bar;
+			epf->bar[doorbell_bar].size = align;
+		} else {
+			pci_epf_free_doorbell(epf);
+		}
+	}
+
 	ret = pci_epf_test_alloc_space(epf);
 	if (ret)
 		return ret;
 
+	if (doorbell_bar > 0) {
+		struct pci_epf_test_reg *reg = epf_test->reg[test_reg_bar];
+
+		reg->doorbell_addr = doorbell_addr & (align - 1);
+		reg->doorbell_data = msg->data;
+		reg->doorbell_bar = doorbell_bar;
+	}
+
 	return 0;
 }
 

-- 
2.34.1