[PATCH V3] PCI: exynos: add support for MSI

[Jingoo Han]

This patch adds support for Message Signaled Interrupt in the
Exynos PCIe diver using Synopsys designware PCIe core IP.

Signed-off-by: Siva Reddy Kallam <siva.kallam@xxxxxxxxxxx>
Signed-off-by: Srikanth T Shivanand <ts.srikanth@xxxxxxxxxxx>
Signed-off-by: Jingoo Han <jg1.han@xxxxxxxxxxx>
Cc: Pratyush Anand <pratyush.anand@xxxxxx>
Cc: Mohit KUMAR <Mohit.KUMAR@xxxxxx>
---
Changes since v2:
- fixed MAX_MSI_CTRLS because MAX_MSI_IRQS is 32 only
- used __get_free_pages() to allocate msi_data
- used one msi_data and msi_irq_in_use per one RC
- used irq_domain to represent the MSI controller
- removed msi-base irq number from device tree because this is not
  a hardware property.

Changes since v1:
- removed unnecessary exynos_pcie_clear_irq_level()
- updated the bindings documentation
- used new msi_chip infrastructure
- removed ARCH_SUPPORTS_MSI
- replaced #ifdef guards with IS_ENABLED(CONFIG_PCI_MSI)

 drivers/pci/host/pci-exynos.c      |   44 +++++++
 drivers/pci/host/pcie-designware.c |  240 ++++++++++++++++++++++++++++++++++++
 drivers/pci/host/pcie-designware.h |   14 +++
 3 files changed, 298 insertions(+)

diff --git a/drivers/pci/host/pci-exynos.c b/drivers/pci/host/pci-exynos.c
index 94e096b..f062aca 100644
--- a/drivers/pci/host/pci-exynos.c
+++ b/drivers/pci/host/pci-exynos.c
@@ -48,6 +48,7 @@ struct exynos_pcie {
 #define PCIE_IRQ_SPECIAL		0x008
 #define PCIE_IRQ_EN_PULSE		0x00c
 #define PCIE_IRQ_EN_LEVEL		0x010
+#define IRQ_MSI_ENABLE			(0x1 << 2)
 #define PCIE_IRQ_EN_SPECIAL		0x014
 #define PCIE_PWR_RESET			0x018
 #define PCIE_CORE_RESET			0x01c
@@ -342,9 +343,36 @@ static irqreturn_t exynos_pcie_irq_handler(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t exynos_pcie_msi_irq_handler(int irq, void *arg)
+{
+	struct pcie_port *pp = arg;
+
+	dw_handle_msi_irq(pp);
+
+	return IRQ_HANDLED;
+}
+
+static void exynos_pcie_msi_init(struct pcie_port *pp)
+{
+	u32 val;
+	struct exynos_pcie *exynos_pcie = to_exynos_pcie(pp);
+
+	dw_pcie_msi_init(pp);
+
+	/* enable MSI interrupt */
+	val = exynos_elb_readl(exynos_pcie, PCIE_IRQ_EN_LEVEL);
+	val |= IRQ_MSI_ENABLE;
+	exynos_elb_writel(exynos_pcie, val, PCIE_IRQ_EN_LEVEL);
+	return;
+}
+
 static void exynos_pcie_enable_interrupts(struct pcie_port *pp)
 {
 	exynos_pcie_enable_irq_pulse(pp);
+
+	if (IS_ENABLED(CONFIG_PCI_MSI))
+		exynos_pcie_msi_init(pp);
+
 	return;
 }
 
@@ -430,6 +458,22 @@ static int add_pcie_port(struct pcie_port *pp, struct platform_device *pdev)
 		return ret;
 	}
 
+	if (IS_ENABLED(CONFIG_PCI_MSI)) {
+		pp->msi_irq = platform_get_irq(pdev, 0);
+		if (!pp->msi_irq) {
+			dev_err(&pdev->dev, "failed to get msi irq\n");
+			return -ENODEV;
+		}
+
+		ret = devm_request_irq(&pdev->dev, pp->msi_irq,
+					exynos_pcie_msi_irq_handler,
+					IRQF_SHARED, "exynos-pcie", pp);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to request msi irq\n");
+			return ret;
+		}
+	}
+
 	pp->root_bus_nr = -1;
 	pp->ops = &exynos_pcie_host_ops;
 
diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
index c10e9ac..8963017 100644
--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c
@@ -11,8 +11,11 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/msi.h>
 #include <linux/of_address.h>
 #include <linux/pci.h>
 #include <linux/pci_regs.h>
@@ -142,6 +145,204 @@ int dw_pcie_wr_own_conf(struct pcie_port *pp, int where, int size,
 	return ret;
 }
 
+static struct irq_chip dw_msi_irq_chip = {
+	.name = "PCI-MSI",
+	.irq_enable = unmask_msi_irq,
+	.irq_disable = mask_msi_irq,
+	.irq_mask = mask_msi_irq,
+	.irq_unmask = unmask_msi_irq,
+};
+
+/* MSI int handler */
+void dw_handle_msi_irq(struct pcie_port *pp)
+{
+	unsigned long val;
+	int i, pos;
+
+	for (i = 0; i < MAX_MSI_CTRLS; i++) {
+		dw_pcie_rd_own_conf(pp, PCIE_MSI_INTR0_STATUS + i * 12, 4,
+				(u32 *)&val);
+		if (val) {
+			pos = 0;
+			while ((pos = find_next_bit(&val, 32, pos)) != 32) {
+				generic_handle_irq(pp->msi_irq_start
+					+ (i * 32) + pos);
+				pos++;
+			}
+		}
+		dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_STATUS + i * 12, 4, val);
+	}
+}
+
+void dw_pcie_msi_init(struct pcie_port *pp)
+{
+	pp->msi_data = __get_free_pages(GFP_KERNEL, 0);
+
+	/* program the msi_data */
+	dw_pcie_wr_own_conf(pp, PCIE_MSI_ADDR_LO, 4,
+			virt_to_phys((void *)pp->msi_data));
+	dw_pcie_wr_own_conf(pp, PCIE_MSI_ADDR_HI, 4, 0);
+}
+
+static int find_valid_pos0(struct pcie_port *pp, int msgvec, int pos, int *pos0)
+{
+	int flag = 1;
+
+	do {
+		pos = find_next_zero_bit(pp->msi_irq_in_use,
+				MAX_MSI_IRQS, pos);
+		/*if you have reached to the end then get out from here.*/
+		if (pos == MAX_MSI_IRQS)
+			return -ENOSPC;
+		/*
+		 * Check if this position is at correct offset.nvec is always a
+		 * power of two. pos0 must be nvec bit alligned.
+		 */
+		if (pos % msgvec)
+			pos += msgvec - (pos % msgvec);
+		else
+			flag = 0;
+	} while (flag);
+
+	*pos0 = pos;
+	return 0;
+}
+
+static int assign_irq(int no_irqs, struct msi_desc *desc, int *pos)
+{
+	int res, bit, irq, pos0, pos1, i;
+	u32 val;
+	struct pcie_port *pp = sys_to_pcie(desc->dev->bus->sysdata);
+
+	if (!pp) {
+		BUG();
+		return -EINVAL;
+	}
+
+	pos0 = find_first_zero_bit(pp->msi_irq_in_use,
+			MAX_MSI_IRQS);
+	if (pos0 % no_irqs) {
+		if (find_valid_pos0(pp, no_irqs, pos0, &pos0))
+			goto no_valid_irq;
+	}
+	if (no_irqs > 1) {
+		pos1 = find_next_bit(pp->msi_irq_in_use,
+				MAX_MSI_IRQS, pos0);
+		/* there must be nvec number of consecutive free bits */
+		while ((pos1 - pos0) < no_irqs) {
+			if (find_valid_pos0(pp, no_irqs, pos1, &pos0))
+				goto no_valid_irq;
+			pos1 = find_next_bit(pp->msi_irq_in_use,
+					MAX_MSI_IRQS, pos0);
+		}
+	}
+
+	irq = (pp->msi_irq_start + pos0);
+
+	if ((irq + no_irqs) > (pp->msi_irq_start + MAX_MSI_IRQS-1))
+		goto no_valid_irq;
+
+	i = 0;
+	while (i < no_irqs) {
+		set_bit(pos0 + i, pp->msi_irq_in_use);
+		irq_alloc_descs((irq + i), (irq + i), 1, 0);
+		irq_set_msi_desc(irq + i, desc);
+		/*Enable corresponding interrupt in MSI interrupt controller */
+		res = ((pos0 + i) / 32) * 12;
+		bit = (pos0 + i) % 32;
+		dw_pcie_rd_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4, &val);
+		val |= 1 << bit;
+		dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4, val);
+		i++;
+	}
+
+	*pos = pos0;
+	return irq;
+
+no_valid_irq:
+	*pos = pos0;
+	return -ENOSPC;
+}
+
+static void clear_irq(unsigned int irq)
+{
+	int res, bit, val, pos;
+	struct irq_desc *desc;
+	struct msi_desc *msi;
+	struct pcie_port *pp;
+
+	/* get the port structure */
+	desc = irq_to_desc(irq);
+	msi = irq_desc_get_msi_desc(desc);
+	pp = sys_to_pcie(msi->dev->bus->sysdata);
+	if (!pp) {
+		BUG();
+		return;
+	}
+
+	pos = irq - pp->msi_irq_start;
+
+	irq_free_desc(irq);
+
+	clear_bit(pos, pp->msi_irq_in_use);
+
+	/* Disable corresponding interrupt on MSI interrupt controller */
+	res = (pos / 32) * 12;
+	bit = pos % 32;
+	dw_pcie_rd_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4, &val);
+	val &= ~(1 << bit);
+	dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4, val);
+}
+
+static int dw_msi_setup_irq(struct msi_chip *chip, struct pci_dev *pdev,
+			struct msi_desc *desc)
+{
+	int irq, pos, msgvec;
+	u16 msg_ctr;
+	struct msi_msg msg;
+	struct pcie_port *pp = sys_to_pcie(pdev->bus->sysdata);
+
+	if (!pp) {
+		BUG();
+		return -EINVAL;
+	}
+
+	pci_read_config_word(pdev, desc->msi_attrib.pos+PCI_MSI_FLAGS,
+				&msg_ctr);
+	msgvec = (msg_ctr&PCI_MSI_FLAGS_QSIZE) >> 4;
+	if (msgvec == 0)
+		msgvec = (msg_ctr & PCI_MSI_FLAGS_QMASK) >> 1;
+	if (msgvec > 5)
+		msgvec = 0;
+
+	irq = assign_irq((1 << msgvec), desc, &pos);
+	if (irq < 0)
+		return irq;
+
+	msg_ctr &= ~PCI_MSI_FLAGS_QSIZE;
+	msg_ctr |= msgvec << 4;
+	pci_write_config_word(pdev, desc->msi_attrib.pos + PCI_MSI_FLAGS,
+				msg_ctr);
+	desc->msi_attrib.multiple = msgvec;
+
+	msg.address_lo = virt_to_phys((void *)pp->msi_data);
+	msg.address_hi = 0x0;
+	msg.data = pos;
+	write_msi_msg(irq, &msg);
+
+	return 0;
+}
+
+static void dw_msi_teardown_irq(struct msi_chip *chip, unsigned int irq)
+{
+	clear_irq(irq);
+}
+
+static struct msi_chip dw_pcie_msi_chip = {
+	.setup_irq = dw_msi_setup_irq,
+	.teardown_irq = dw_msi_teardown_irq,
+};
+
 int dw_pcie_link_up(struct pcie_port *pp)
 {
 	if (pp->ops->link_up)
@@ -150,6 +351,20 @@ int dw_pcie_link_up(struct pcie_port *pp)
 		return 0;
 }
 
+static int dw_pcie_msi_map(struct irq_domain *domain, unsigned int irq,
+			irq_hw_number_t hwirq)
+{
+	irq_set_chip_and_handler(irq, &dw_msi_irq_chip, handle_simple_irq);
+	irq_set_chip_data(irq, domain->host_data);
+	set_irq_flags(irq, IRQF_VALID);
+
+	return 0;
+}
+
+static const struct irq_domain_ops msi_domain_ops = {
+	.map = dw_pcie_msi_map,
+};
+
 int __init dw_pcie_host_init(struct pcie_port *pp)
 {
 	struct device_node *np = pp->dev->of_node;
@@ -157,6 +372,8 @@ int __init dw_pcie_host_init(struct pcie_port *pp)
 	struct of_pci_range_parser parser;
 	u32 val;
 
+	struct irq_domain *irq_domain;
+
 	if (of_pci_range_parser_init(&parser, np)) {
 		dev_err(pp->dev, "missing ranges property\n");
 		return -EINVAL;
@@ -223,6 +440,18 @@ int __init dw_pcie_host_init(struct pcie_port *pp)
 		return -EINVAL;
 	}
 
+	if (IS_ENABLED(CONFIG_PCI_MSI)) {
+		irq_domain = irq_domain_add_linear(pp->dev->of_node,
+					MAX_MSI_IRQS, &msi_domain_ops,
+					&dw_pcie_msi_chip);
+		if (!irq_domain) {
+			dev_err(pp->dev, "irq domain init failed\n");
+			return -ENXIO;
+		}
+
+		pp->msi_irq_start = irq_find_mapping(irq_domain, 0);
+	}
+
 	if (pp->ops->host_init)
 		pp->ops->host_init(pp);
 
@@ -485,10 +714,21 @@ int dw_pcie_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
 	return pp->irq;
 }
 
+static void dw_pcie_add_bus(struct pci_bus *bus)
+{
+	if (IS_ENABLED(CONFIG_PCI_MSI)) {
+		struct pcie_port *pp = sys_to_pcie(bus->sysdata);
+
+		dw_pcie_msi_chip.dev = pp->dev;
+		bus->msi = &dw_pcie_msi_chip;
+	}
+}
+
 static struct hw_pci dw_pci = {
 	.setup		= dw_pcie_setup,
 	.scan		= dw_pcie_scan_bus,
 	.map_irq	= dw_pcie_map_irq,
+	.add_bus	= dw_pcie_add_bus,
 };
 
 void dw_pcie_setup_rc(struct pcie_port *pp)
diff --git a/drivers/pci/host/pcie-designware.h b/drivers/pci/host/pcie-designware.h
index 133820f..faccbbf 100644
--- a/drivers/pci/host/pcie-designware.h
+++ b/drivers/pci/host/pcie-designware.h
@@ -20,6 +20,14 @@ struct pcie_port_info {
 	phys_addr_t	mem_bus_addr;
 };
 
+/*
+ * Maximum number of MSI IRQs can be 256 per controller. But keep
+ * it 32 as of now. Probably we will never need more than 32. If needed,
+ * then increment it in multiple of 32.
+ */
+#define MAX_MSI_IRQS			32
+#define MAX_MSI_CTRLS			(MAX_MSI_IRQS / 32)
+
 struct pcie_port {
 	struct device		*dev;
 	u8			root_bus_nr;
@@ -38,6 +46,10 @@ struct pcie_port {
 	int			irq;
 	u32			lanes;
 	struct pcie_host_ops	*ops;
+	int			msi_irq;
+	int			msi_irq_start;
+	unsigned long		msi_data;
+	DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
 };
 
 struct pcie_host_ops {
@@ -57,6 +69,8 @@ int cfg_read(void __iomem *addr, int where, int size, u32 *val);
 int cfg_write(void __iomem *addr, int where, int size, u32 val);
 int dw_pcie_wr_own_conf(struct pcie_port *pp, int where, int size, u32 val);
 int dw_pcie_rd_own_conf(struct pcie_port *pp, int where, int size, u32 *val);
+void dw_handle_msi_irq(struct pcie_port *pp);
+void dw_pcie_msi_init(struct pcie_port *pp);
 int dw_pcie_link_up(struct pcie_port *pp);
 void dw_pcie_setup_rc(struct pcie_port *pp);
 int dw_pcie_host_init(struct pcie_port *pp);
-- 
1.7.10.4


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