[U-Boot] [PATCHv4 10/12] dm: pci: add APIs for MPS and MRRS accessors

[Z.q. Hou]

From: Hou Zhiqiang <Zhiqiang.Hou at nxp.com>

This patch introduce APIs for getting and updating the MPS
and MRRS fields of Device capability Device control register.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou at nxp.com>
---
V4:
 - New patch

 drivers/pci/pci-uclass.c | 92 ++++++++++++++++++++++++++++++++++++++++
 include/pci.h            | 13 ++++++
 2 files changed, 105 insertions(+)

diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index 4bb30f5d2b..b2d295435a 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -7,6 +7,7 @@
 #include <common.h>
 #include <dm.h>
 #include <errno.h>
+#include <linux/log2.h>
 #include <pci.h>
 #include <asm/io.h>
 #include <dm/device-internal.h>
@@ -1596,6 +1597,97 @@ int dm_pci_capability_clear_and_set_dword(struct udevice *dev, int cap,
 					       set, PCI_SIZE_32);
 }
 
+/**
+ * dm_pci_get_readrq - get PCI Express read request size
+ * @dev: PCI device to query
+ *
+ * Returns maximum memory read request in bytes
+ *    or appropriate error value.
+ */
+int dm_pci_get_readrq(struct udevice *dev)
+{
+	u16 ctl;
+	int ret;
+
+	ret = dm_pci_capability_read_word(dev, PCI_CAP_ID_EXP,
+					  PCI_EXP_DEVCTL, &ctl);
+	if (ret)
+		return ret;
+
+	return 128 << ((ctl & PCI_EXP_DEVCTL_READRQ) >> 12);
+}
+
+/**
+ * dm_pci_set_readrq - set PCI Express maximum memory read request
+ * @dev: PCI device to query
+ * @rq: maximum memory read count in bytes
+ *    valid values are 128, 256, 512, 1024, 2048, 4096
+ */
+int dm_pci_set_readrq(struct udevice *dev, int rq)
+{
+	u16 val;
+
+	if (rq < 128 || rq > 4096 || !is_power_of_2(rq))
+		return -EINVAL;
+
+	val = (ffs(rq) - 8) << 12;
+
+	return dm_pci_capability_clear_and_set_word(dev, PCI_CAP_ID_EXP,
+						    PCI_EXP_DEVCTL,
+						    PCI_EXP_DEVCTL_READRQ,
+						    val);
+}
+
+/**
+ * dm_pci_get_mps - get PCI Express maximum payload size
+ * @dev: PCI device to query
+ *
+ * Returns maximum payload size in bytes
+ */
+int dm_pci_get_mps(struct udevice *dev)
+{
+	u16 ctl;
+	int ret;
+
+	ret = dm_pci_capability_read_word(dev, PCI_CAP_ID_EXP,
+					  PCI_EXP_DEVCTL, &ctl);
+	if (ret)
+		return ret;
+
+	return 128 << ((ctl & PCI_EXP_DEVCTL_PAYLOAD) >> 5);
+}
+
+/**
+ * dm_pci_set_mps - set PCI Express maximum payload size
+ * @dev: PCI device to query
+ * @mps: maximum payload size in bytes
+ *    valid values are 128, 256, 512, 1024, 2048, 4096
+ */
+int dm_pci_set_mps(struct udevice *dev, int mps)
+{
+	u16 val, cap;
+	int ret;
+
+	if (mps < 128 || mps > 4096 || !is_power_of_2(mps))
+		return -EINVAL;
+
+	ret = dm_pci_capability_read_word(dev, PCI_CAP_ID_EXP,
+					  PCI_EXP_DEVCAP, &cap);
+	if (ret)
+		return ret;
+
+	val = ffs(mps) - 8;
+	if (val > (cap & PCI_EXP_DEVCAP_PAYLOAD))
+		return -EINVAL;
+
+	val <<= 5;
+
+	return dm_pci_capability_clear_and_set_word(dev, PCI_CAP_ID_EXP,
+						    PCI_EXP_DEVCTL,
+						    PCI_EXP_DEVCTL_PAYLOAD,
+						    val);
+}
+
 UCLASS_DRIVER(pci) = {
 	.id		= UCLASS_PCI,
 	.name		= "pci",
diff --git a/include/pci.h b/include/pci.h
index d7b6d9f4ff..b48df8a363 100644
--- a/include/pci.h
+++ b/include/pci.h
@@ -414,6 +414,14 @@
 #define PCI_MAX_PCI_DEVICES	32
 #define PCI_MAX_PCI_FUNCTIONS	8
 
+/* PCI Express capability registers */
+#define PCI_EXP_DEVCAP			4	/* Device capabilities */
+#define  PCI_EXP_DEVCAP_PAYLOAD		0x0007	/* Max_Payload_Size */
+
+#define PCI_EXP_DEVCTL			8	/* Device Control */
+#define  PCI_EXP_DEVCTL_PAYLOAD		0x00e0	/* Max_Payload_Size */
+#define  PCI_EXP_DEVCTL_READRQ		0x7000	/* Max_Read_Request_Size */
+
 #define PCI_FIND_CAP_TTL 0x48
 #define CAP_START_POS 0x40
 
@@ -1425,6 +1433,11 @@ int dm_pci_capability_clear_and_set_word(struct udevice *dev, int cap,
 int dm_pci_capability_clear_and_set_dword(struct udevice *dev, int cap,
 					  int pos, u32 clear, u32 set);
 
+int dm_pci_get_readrq(struct udevice *dev);
+int dm_pci_set_readrq(struct udevice *dev, int rq);
+int dm_pci_get_mps(struct udevice *dev);
+int dm_pci_set_mps(struct udevice *dev, int mps);
+
 #define dm_pci_virt_to_bus(dev, addr, flags) \
 	dm_pci_phys_to_bus(dev, (virt_to_phys(addr)), (flags))
 #define dm_pci_bus_to_virt(dev, addr, flags, len, map_flags) \
-- 
2.17.1