Merge branch 'iosm-driver'

M Chetan Kumar says:

====================
net: iosm: PCIe Driver for Intel M.2 Modem

The IOSM (IPC over Shared Memory) driver is a PCIe host driver implemented
for linux or chrome platform for data exchange over PCIe interface between
Host platform & Intel M.2 Modem. The driver exposes interface conforming to
the MBIM protocol. Any front end application ( eg: Modem Manager) could
easily manage the MBIM interface to enable data communication towards WWAN.

Intel M.2 modem uses 2 BAR regions. The first region is dedicated to Doorbell
register for IRQs and the second region is used as scratchpad area for book
keeping modem execution stage details along with host system shared memory
region context details. The upper edge of the driver exposes the control and
data channels for user space application interaction. At lower edge these data
and control channels are associated to pipes. The pipes are lowest level
interfaces used over PCIe as a logical channel for message exchange. A single
channel maps to UL and DL pipe and are initialized on device open.

On UL path, driver copies application sent data to SKBs associate it with
transfer descriptor and puts it on to ring buffer for DMA transfer. Once
information has been updated in shared memory region, host gives a Doorbell
to modem to perform DMA and modem uses MSI to communicate back to host.
For receiving data in DL path, SKBs are pre-allocated during pipe open and
transfer descriptors are given to modem for DMA transfer.

The driver exposes two types of ports, namely "wwan0mbim0", a char device node
which is used for MBIM control operation and "wwan0-x",(x = 0,1,2..7) network
interfaces for IP data communication.
1) MBIM Control Interface:
This node exposes an interface between modem and application using char device
exposed by "IOSM" driver to establish and manage the MBIM data communication
with PCIe based Intel M.2 Modems.

2) MBIM Data Interface:
The IOSM driver exposes IP link interface "wwan0-x" of type "wwan" for IP traffic.
Iproute network utility is used for creating "wwan0-x" network interface and for
associating it with MBIM IP session. The Driver supports upto 8 IP sessions for
simultaneous IP communication.

This applies on top of WWAN core rtnetlink series posted here:
https://lore.kernel.org/netdev/1623486057-13075-1-git-send-email-loic.poulain@linaro.org/

Also driver has been compiled and tested on top of netdev net-next tree.
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 579 insertions, 0 deletions

diff --git a/drivers/net/wwan/iosm/iosm_ipc_pcie.c b/drivers/net/wwan/iosm/iosm_ipc_pcie.c
new file mode 100644
index 000000000000..ac6baddfde61
--- /dev/null
+++ b/drivers/net/wwan/iosm/iosm_ipc_pcie.c
@@ -0,0 +1,579 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020-21 Intel Corporation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/bitfield.h>
+#include <linux/module.h>
+#include <net/rtnetlink.h>
+
+#include "iosm_ipc_imem.h"
+#include "iosm_ipc_pcie.h"
+#include "iosm_ipc_protocol.h"
+
+MODULE_DESCRIPTION("IOSM Driver");
+MODULE_LICENSE("GPL v2");
+
+/* WWAN GUID */
+static guid_t wwan_acpi_guid = GUID_INIT(0xbad01b75, 0x22a8, 0x4f48, 0x87, 0x92,
+				       0xbd, 0xde, 0x94, 0x67, 0x74, 0x7d);
+
+static void ipc_pcie_resources_release(struct iosm_pcie *ipc_pcie)
+{
+	/* Free the MSI resources. */
+	ipc_release_irq(ipc_pcie);
+
+	/* Free mapped doorbell scratchpad bus memory into CPU space. */
+	iounmap(ipc_pcie->scratchpad);
+
+	/* Free mapped IPC_REGS bus memory into CPU space. */
+	iounmap(ipc_pcie->ipc_regs);
+
+	/* Releases all PCI I/O and memory resources previously reserved by a
+	 * successful call to pci_request_regions.  Call this function only
+	 * after all use of the PCI regions has ceased.
+	 */
+	pci_release_regions(ipc_pcie->pci);
+}
+
+static void ipc_pcie_cleanup(struct iosm_pcie *ipc_pcie)
+{
+	/* Free the shared memory resources. */
+	ipc_imem_cleanup(ipc_pcie->imem);
+
+	ipc_pcie_resources_release(ipc_pcie);
+
+	/* Signal to the system that the PCI device is not in use. */
+	pci_disable_device(ipc_pcie->pci);
+}
+
+static void ipc_pcie_deinit(struct iosm_pcie *ipc_pcie)
+{
+	kfree(ipc_pcie->imem);
+	kfree(ipc_pcie);
+}
+
+static void ipc_pcie_remove(struct pci_dev *pci)
+{
+	struct iosm_pcie *ipc_pcie = pci_get_drvdata(pci);
+
+	ipc_pcie_cleanup(ipc_pcie);
+
+	ipc_pcie_deinit(ipc_pcie);
+}
+
+static int ipc_pcie_resources_request(struct iosm_pcie *ipc_pcie)
+{
+	struct pci_dev *pci = ipc_pcie->pci;
+	u32 cap = 0;
+	u32 ret;
+
+	/* Reserved PCI I/O and memory resources.
+	 * Mark all PCI regions associated with PCI device pci as
+	 * being reserved by owner IOSM_IPC.
+	 */
+	ret = pci_request_regions(pci, "IOSM_IPC");
+	if (ret) {
+		dev_err(ipc_pcie->dev, "failed pci request regions");
+		goto pci_request_region_fail;
+	}
+
+	/* Reserve the doorbell IPC REGS memory resources.
+	 * Remap the memory into CPU space. Arrange for the physical address
+	 * (BAR) to be visible from this driver.
+	 * pci_ioremap_bar() ensures that the memory is marked uncachable.
+	 */
+	ipc_pcie->ipc_regs = pci_ioremap_bar(pci, ipc_pcie->ipc_regs_bar_nr);
+
+	if (!ipc_pcie->ipc_regs) {
+		dev_err(ipc_pcie->dev, "IPC REGS ioremap error");
+		ret = -EBUSY;
+		goto ipc_regs_remap_fail;
+	}
+
+	/* Reserve the MMIO scratchpad memory resources.
+	 * Remap the memory into CPU space. Arrange for the physical address
+	 * (BAR) to be visible from this driver.
+	 * pci_ioremap_bar() ensures that the memory is marked uncachable.
+	 */
+	ipc_pcie->scratchpad =
+		pci_ioremap_bar(pci, ipc_pcie->scratchpad_bar_nr);
+
+	if (!ipc_pcie->scratchpad) {
+		dev_err(ipc_pcie->dev, "doorbell scratchpad ioremap error");
+		ret = -EBUSY;
+		goto scratch_remap_fail;
+	}
+
+	/* Install the irq handler triggered by CP. */
+	ret = ipc_acquire_irq(ipc_pcie);
+	if (ret) {
+		dev_err(ipc_pcie->dev, "acquiring MSI irq failed!");
+		goto irq_acquire_fail;
+	}
+
+	/* Enable bus-mastering for the IOSM IPC device. */
+	pci_set_master(pci);
+
+	/* Enable LTR if possible
+	 * This is needed for L1.2!
+	 */
+	pcie_capability_read_dword(ipc_pcie->pci, PCI_EXP_DEVCAP2, &cap);
+	if (cap & PCI_EXP_DEVCAP2_LTR)
+		pcie_capability_set_word(ipc_pcie->pci, PCI_EXP_DEVCTL2,
+					 PCI_EXP_DEVCTL2_LTR_EN);
+
+	dev_dbg(ipc_pcie->dev, "link between AP and CP is fully on");
+
+	return ret;
+
+irq_acquire_fail:
+	iounmap(ipc_pcie->scratchpad);
+scratch_remap_fail:
+	iounmap(ipc_pcie->ipc_regs);
+ipc_regs_remap_fail:
+	pci_release_regions(pci);
+pci_request_region_fail:
+	return ret;
+}
+
+bool ipc_pcie_check_aspm_enabled(struct iosm_pcie *ipc_pcie,
+				 bool parent)
+{
+	struct pci_dev *pdev;
+	u16 value = 0;
+	u32 enabled;
+
+	if (parent)
+		pdev = ipc_pcie->pci->bus->self;
+	else
+		pdev = ipc_pcie->pci;
+
+	pcie_capability_read_word(pdev, PCI_EXP_LNKCTL, &value);
+	enabled = value & PCI_EXP_LNKCTL_ASPMC;
+	dev_dbg(ipc_pcie->dev, "ASPM L1: 0x%04X 0x%03X", pdev->device, value);
+
+	return (enabled == PCI_EXP_LNKCTL_ASPM_L1 ||
+		enabled == PCI_EXP_LNKCTL_ASPMC);
+}
+
+bool ipc_pcie_check_data_link_active(struct iosm_pcie *ipc_pcie)
+{
+	struct pci_dev *parent;
+	u16 link_status = 0;
+
+	if (!ipc_pcie->pci->bus || !ipc_pcie->pci->bus->self) {
+		dev_err(ipc_pcie->dev, "root port not found");
+		return false;
+	}
+
+	parent = ipc_pcie->pci->bus->self;
+
+	pcie_capability_read_word(parent, PCI_EXP_LNKSTA, &link_status);
+	dev_dbg(ipc_pcie->dev, "Link status: 0x%04X", link_status);
+
+	return link_status & PCI_EXP_LNKSTA_DLLLA;
+}
+
+static bool ipc_pcie_check_aspm_supported(struct iosm_pcie *ipc_pcie,
+					  bool parent)
+{
+	struct pci_dev *pdev;
+	u32 support;
+	u32 cap = 0;
+
+	if (parent)
+		pdev = ipc_pcie->pci->bus->self;
+	else
+		pdev = ipc_pcie->pci;
+	pcie_capability_read_dword(pdev, PCI_EXP_LNKCAP, &cap);
+	support = u32_get_bits(cap, PCI_EXP_LNKCAP_ASPMS);
+	if (support < PCI_EXP_LNKCTL_ASPM_L1) {
+		dev_dbg(ipc_pcie->dev, "ASPM L1 not supported: 0x%04X",
+			pdev->device);
+		return false;
+	}
+	return true;
+}
+
+void ipc_pcie_config_aspm(struct iosm_pcie *ipc_pcie)
+{
+	bool parent_aspm_enabled, dev_aspm_enabled;
+
+	/* check if both root port and child supports ASPM L1 */
+	if (!ipc_pcie_check_aspm_supported(ipc_pcie, true) ||
+	    !ipc_pcie_check_aspm_supported(ipc_pcie, false))
+		return;
+
+	parent_aspm_enabled = ipc_pcie_check_aspm_enabled(ipc_pcie, true);
+	dev_aspm_enabled = ipc_pcie_check_aspm_enabled(ipc_pcie, false);
+
+	dev_dbg(ipc_pcie->dev, "ASPM parent: %s device: %s",
+		parent_aspm_enabled ? "Enabled" : "Disabled",
+		dev_aspm_enabled ? "Enabled" : "Disabled");
+}
+
+/* Initializes PCIe endpoint configuration */
+static void ipc_pcie_config_init(struct iosm_pcie *ipc_pcie)
+{
+	/* BAR0 is used for doorbell */
+	ipc_pcie->ipc_regs_bar_nr = IPC_DOORBELL_BAR0;
+
+	/* update HW configuration */
+	ipc_pcie->scratchpad_bar_nr = IPC_SCRATCHPAD_BAR2;
+	ipc_pcie->doorbell_reg_offset = IPC_DOORBELL_CH_OFFSET;
+	ipc_pcie->doorbell_write = IPC_WRITE_PTR_REG_0;
+	ipc_pcie->doorbell_capture = IPC_CAPTURE_PTR_REG_0;
+}
+
+/* This will read the BIOS WWAN RTD3 settings:
+ * D0L1.2/D3L2/Disabled
+ */
+static enum ipc_pcie_sleep_state ipc_pcie_read_bios_cfg(struct device *dev)
+{
+	union acpi_object *object;
+	acpi_handle handle_acpi;
+
+	handle_acpi = ACPI_HANDLE(dev);
+	if (!handle_acpi) {
+		pr_debug("pci device is NOT ACPI supporting device\n");
+		goto default_ret;
+	}
+
+	object = acpi_evaluate_dsm(handle_acpi, &wwan_acpi_guid, 0, 3, NULL);
+
+	if (object && object->integer.value == 3)
+		return IPC_PCIE_D3L2;
+
+default_ret:
+	return IPC_PCIE_D0L12;
+}
+
+static int ipc_pcie_probe(struct pci_dev *pci,
+			  const struct pci_device_id *pci_id)
+{
+	struct iosm_pcie *ipc_pcie = kzalloc(sizeof(*ipc_pcie), GFP_KERNEL);
+
+	pr_debug("Probing device 0x%X from the vendor 0x%X", pci_id->device,
+		 pci_id->vendor);
+
+	if (!ipc_pcie)
+		goto ret_fail;
+
+	/* Initialize ipc dbg component for the PCIe device */
+	ipc_pcie->dev = &pci->dev;
+
+	/* Set the driver specific data. */
+	pci_set_drvdata(pci, ipc_pcie);
+
+	/* Save the address of the PCI device configuration. */
+	ipc_pcie->pci = pci;
+
+	/* Update platform configuration */
+	ipc_pcie_config_init(ipc_pcie);
+
+	/* Initialize the device before it is used. Ask low-level code
+	 * to enable I/O and memory. Wake up the device if it was suspended.
+	 */
+	if (pci_enable_device(pci)) {
+		dev_err(ipc_pcie->dev, "failed to enable the AP PCIe device");
+		/* If enable of PCIe device has failed then calling
+		 * ipc_pcie_cleanup will panic the system. More over
+		 * ipc_pcie_cleanup() is required to be called after
+		 * ipc_imem_mount()
+		 */
+		goto pci_enable_fail;
+	}
+
+	ipc_pcie_config_aspm(ipc_pcie);
+	dev_dbg(ipc_pcie->dev, "PCIe device enabled.");
+
+	/* Read WWAN RTD3 BIOS Setting
+	 */
+	ipc_pcie->d3l2_support = ipc_pcie_read_bios_cfg(&pci->dev);
+
+	ipc_pcie->suspend = 0;
+
+	if (ipc_pcie_resources_request(ipc_pcie))
+		goto resources_req_fail;
+
+	/* Establish the link to the imem layer. */
+	ipc_pcie->imem = ipc_imem_init(ipc_pcie, pci->device,
+				       ipc_pcie->scratchpad, ipc_pcie->dev);
+	if (!ipc_pcie->imem) {
+		dev_err(ipc_pcie->dev, "failed to init imem");
+		goto imem_init_fail;
+	}
+
+	return 0;
+
+imem_init_fail:
+	ipc_pcie_resources_release(ipc_pcie);
+resources_req_fail:
+	pci_disable_device(pci);
+pci_enable_fail:
+	kfree(ipc_pcie);
+ret_fail:
+	return -EIO;
+}
+
+static const struct pci_device_id iosm_ipc_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, INTEL_CP_DEVICE_7560_ID) },
+	{}
+};
+
+/* Enter sleep in s2idle case
+ */
+static int __maybe_unused ipc_pcie_suspend_s2idle(struct iosm_pcie *ipc_pcie)
+{
+	ipc_cp_irq_sleep_control(ipc_pcie, IPC_MEM_DEV_PM_FORCE_SLEEP);
+
+	/* Complete all memory stores before setting bit */
+	smp_mb__before_atomic();
+
+	set_bit(0, &ipc_pcie->suspend);
+
+	/* Complete all memory stores after setting bit */
+	smp_mb__after_atomic();
+
+	ipc_imem_pm_s2idle_sleep(ipc_pcie->imem, true);
+
+	return 0;
+}
+
+/* Resume from sleep in s2idle case
+ */
+static int __maybe_unused ipc_pcie_resume_s2idle(struct iosm_pcie *ipc_pcie)
+{
+	ipc_cp_irq_sleep_control(ipc_pcie, IPC_MEM_DEV_PM_FORCE_ACTIVE);
+
+	ipc_imem_pm_s2idle_sleep(ipc_pcie->imem, false);
+
+	/* Complete all memory stores before clearing bit. */
+	smp_mb__before_atomic();
+
+	clear_bit(0, &ipc_pcie->suspend);
+
+	/* Complete all memory stores after clearing bit. */
+	smp_mb__after_atomic();
+	return 0;
+}
+
+int __maybe_unused ipc_pcie_suspend(struct iosm_pcie *ipc_pcie)
+{
+	struct pci_dev *pdev;
+	int ret;
+
+	pdev = ipc_pcie->pci;
+
+	/* Execute D3 one time. */
+	if (pdev->current_state != PCI_D0) {
+		dev_dbg(ipc_pcie->dev, "done for PM=%d", pdev->current_state);
+		return 0;
+	}
+
+	/* The HAL shall ask the shared memory layer whether D3 is allowed. */
+	ipc_imem_pm_suspend(ipc_pcie->imem);
+
+	/* Save the PCI configuration space of a device before suspending. */
+	ret = pci_save_state(pdev);
+
+	if (ret) {
+		dev_err(ipc_pcie->dev, "pci_save_state error=%d", ret);
+		return ret;
+	}
+
+	/* Set the power state of a PCI device.
+	 * Transition a device to a new power state, using the device's PCI PM
+	 * registers.
+	 */
+	ret = pci_set_power_state(pdev, PCI_D3cold);
+
+	if (ret) {
+		dev_err(ipc_pcie->dev, "pci_set_power_state error=%d", ret);
+		return ret;
+	}
+
+	dev_dbg(ipc_pcie->dev, "SUSPEND done");
+	return ret;
+}
+
+int __maybe_unused ipc_pcie_resume(struct iosm_pcie *ipc_pcie)
+{
+	int ret;
+
+	/* Set the power state of a PCI device.
+	 * Transition a device to a new power state, using the device's PCI PM
+	 * registers.
+	 */
+	ret = pci_set_power_state(ipc_pcie->pci, PCI_D0);
+
+	if (ret) {
+		dev_err(ipc_pcie->dev, "pci_set_power_state error=%d", ret);
+		return ret;
+	}
+
+	pci_restore_state(ipc_pcie->pci);
+
+	/* The HAL shall inform the shared memory layer that the device is
+	 * active.
+	 */
+	ipc_imem_pm_resume(ipc_pcie->imem);
+
+	dev_dbg(ipc_pcie->dev, "RESUME done");
+	return ret;
+}
+
+static int __maybe_unused ipc_pcie_suspend_cb(struct device *dev)
+{
+	struct iosm_pcie *ipc_pcie;
+	struct pci_dev *pdev;
+
+	pdev = to_pci_dev(dev);
+
+	ipc_pcie = pci_get_drvdata(pdev);
+
+	switch (ipc_pcie->d3l2_support) {
+	case IPC_PCIE_D0L12:
+		ipc_pcie_suspend_s2idle(ipc_pcie);
+		break;
+	case IPC_PCIE_D3L2:
+		ipc_pcie_suspend(ipc_pcie);
+		break;
+	}
+
+	return 0;
+}
+
+static int __maybe_unused ipc_pcie_resume_cb(struct device *dev)
+{
+	struct iosm_pcie *ipc_pcie;
+	struct pci_dev *pdev;
+
+	pdev = to_pci_dev(dev);
+
+	ipc_pcie = pci_get_drvdata(pdev);
+
+	switch (ipc_pcie->d3l2_support) {
+	case IPC_PCIE_D0L12:
+		ipc_pcie_resume_s2idle(ipc_pcie);
+		break;
+	case IPC_PCIE_D3L2:
+		ipc_pcie_resume(ipc_pcie);
+		break;
+	}
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(iosm_ipc_pm, ipc_pcie_suspend_cb, ipc_pcie_resume_cb);
+
+static struct pci_driver iosm_ipc_driver = {
+	.name = KBUILD_MODNAME,
+	.probe = ipc_pcie_probe,
+	.remove = ipc_pcie_remove,
+	.driver = {
+		.pm = &iosm_ipc_pm,
+	},
+	.id_table = iosm_ipc_ids,
+};
+
+int ipc_pcie_addr_map(struct iosm_pcie *ipc_pcie, unsigned char *data,
+		      size_t size, dma_addr_t *mapping, int direction)
+{
+	if (ipc_pcie->pci) {
+		*mapping = dma_map_single(&ipc_pcie->pci->dev, data, size,
+					  direction);
+		if (dma_mapping_error(&ipc_pcie->pci->dev, *mapping)) {
+			dev_err(ipc_pcie->dev, "dma mapping failed");
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+void ipc_pcie_addr_unmap(struct iosm_pcie *ipc_pcie, size_t size,
+			 dma_addr_t mapping, int direction)
+{
+	if (!mapping)
+		return;
+	if (ipc_pcie->pci)
+		dma_unmap_single(&ipc_pcie->pci->dev, mapping, size, direction);
+}
+
+struct sk_buff *ipc_pcie_alloc_local_skb(struct iosm_pcie *ipc_pcie,
+					 gfp_t flags, size_t size)
+{
+	struct sk_buff *skb;
+
+	if (!ipc_pcie || !size) {
+		pr_err("invalid pcie object or size");
+		return NULL;
+	}
+
+	skb = __netdev_alloc_skb(NULL, size, flags);
+	if (!skb)
+		return NULL;
+
+	IPC_CB(skb)->op_type = (u8)UL_DEFAULT;
+	IPC_CB(skb)->mapping = 0;
+
+	return skb;
+}
+
+struct sk_buff *ipc_pcie_alloc_skb(struct iosm_pcie *ipc_pcie, size_t size,
+				   gfp_t flags, dma_addr_t *mapping,
+				   int direction, size_t headroom)
+{
+	struct sk_buff *skb = ipc_pcie_alloc_local_skb(ipc_pcie, flags,
+						       size + headroom);
+	if (!skb)
+		return NULL;
+
+	if (headroom)
+		skb_reserve(skb, headroom);
+
+	if (ipc_pcie_addr_map(ipc_pcie, skb->data, size, mapping, direction)) {
+		dev_kfree_skb(skb);
+		return NULL;
+	}
+
+	BUILD_BUG_ON(sizeof(*IPC_CB(skb)) > sizeof(skb->cb));
+
+	/* Store the mapping address in skb scratch pad for later usage */
+	IPC_CB(skb)->mapping = *mapping;
+	IPC_CB(skb)->direction = direction;
+	IPC_CB(skb)->len = size;
+
+	return skb;
+}
+
+void ipc_pcie_kfree_skb(struct iosm_pcie *ipc_pcie, struct sk_buff *skb)
+{
+	if (!skb)
+		return;
+
+	ipc_pcie_addr_unmap(ipc_pcie, IPC_CB(skb)->len, IPC_CB(skb)->mapping,
+			    IPC_CB(skb)->direction);
+	IPC_CB(skb)->mapping = 0;
+	dev_kfree_skb(skb);
+}
+
+static int __init iosm_ipc_driver_init(void)
+{
+	if (pci_register_driver(&iosm_ipc_driver)) {
+		pr_err("registering of IOSM PCIe driver failed");
+		return -1;
+	}
+
+	return 0;
+}
+
+static void __exit iosm_ipc_driver_exit(void)
+{
+	pci_unregister_driver(&iosm_ipc_driver);
+}
+
+module_init(iosm_ipc_driver_init);
+module_exit(iosm_ipc_driver_exit);