From fa588eba632df14d296436995e6bbea0c146ae77 Mon Sep 17 00:00:00 2001 From: Loic Poulain Date: Fri, 16 Apr 2021 10:36:34 +0200 Subject: [PATCH] net: Add Qcom WWAN control driver The MHI WWWAN control driver allows MHI QCOM-based modems to expose different modem control protocols/ports via the WWAN framework, so that userspace modem tools or daemon (e.g. ModemManager) can control WWAN config and state (APN config, SMS, provider selection...). A QCOM-based modem can expose one or several of the following protocols: - AT: Well known AT commands interactive protocol (microcom, minicom...) - MBIM: Mobile Broadband Interface Model (libmbim, mbimcli) - QMI: QCOM MSM/Modem Interface (libqmi, qmicli) - QCDM: QCOM Modem diagnostic interface (libqcdm) - FIREHOSE: XML-based protocol for Modem firmware management (qmi-firmware-update) Note that this patch is mostly a rework of the earlier MHI UCI tentative that was a generic interface for accessing MHI bus from userspace. As suggested, this new version is WWAN specific and is dedicated to only expose channels used for controlling a modem, and for which related opensource userpace support exist. Signed-off-by: Loic Poulain Signed-off-by: David S. Miller --- drivers/net/wwan/Kconfig | 14 ++ drivers/net/wwan/Makefile | 2 + drivers/net/wwan/mhi_wwan_ctrl.c | 282 +++++++++++++++++++++++++++++++ 3 files changed, 298 insertions(+) create mode 100644 drivers/net/wwan/mhi_wwan_ctrl.c diff --git a/drivers/net/wwan/Kconfig b/drivers/net/wwan/Kconfig index fc3f3a1c80ee..7ad1920120bc 100644 --- a/drivers/net/wwan/Kconfig +++ b/drivers/net/wwan/Kconfig @@ -20,4 +20,18 @@ config WWAN_CORE To compile this driver as a module, choose M here: the module will be called wwan. +config MHI_WWAN_CTRL + tristate "MHI WWAN control driver for QCOM-based PCIe modems" + select WWAN_CORE + depends on MHI_BUS + help + MHI WWAN CTRL allows QCOM-based PCIe modems to expose different modem + control protocols/ports to userspace, including AT, MBIM, QMI, DIAG + and FIREHOSE. These protocols can be accessed directly from userspace + (e.g. AT commands) or via libraries/tools (e.g. libmbim, libqmi, + libqcdm...). + + To compile this driver as a module, choose M here: the module will be + called mhi_wwan_ctrl. + endif # WWAN diff --git a/drivers/net/wwan/Makefile b/drivers/net/wwan/Makefile index 934590b9e47d..556cd90958ca 100644 --- a/drivers/net/wwan/Makefile +++ b/drivers/net/wwan/Makefile @@ -5,3 +5,5 @@ obj-$(CONFIG_WWAN_CORE) += wwan.o wwan-objs += wwan_core.o + +obj-$(CONFIG_MHI_WWAN_CTRL) += mhi_wwan_ctrl.o diff --git a/drivers/net/wwan/mhi_wwan_ctrl.c b/drivers/net/wwan/mhi_wwan_ctrl.c new file mode 100644 index 000000000000..11475ade4be5 --- /dev/null +++ b/drivers/net/wwan/mhi_wwan_ctrl.c @@ -0,0 +1,282 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2021, Linaro Ltd */ +#include +#include +#include +#include +#include + +/* MHI wwan flags */ +#define MHI_WWAN_DL_CAP BIT(0) +#define MHI_WWAN_UL_CAP BIT(1) +#define MHI_WWAN_RX_REFILL BIT(2) + +#define MHI_WWAN_MAX_MTU 0x8000 + +struct mhi_wwan_dev { + /* Lower level is a mhi dev, upper level is a wwan port */ + struct mhi_device *mhi_dev; + struct wwan_port *wwan_port; + + /* State and capabilities */ + unsigned long flags; + size_t mtu; + + /* Protect against concurrent TX and TX-completion (bh) */ + spinlock_t tx_lock; + + /* Protect RX budget and rx_refill scheduling */ + spinlock_t rx_lock; + struct work_struct rx_refill; + + /* RX budget is initially set to the size of the MHI RX queue and is + * used to limit the number of allocated and queued packets. It is + * decremented on data queueing and incremented on data release. + */ + unsigned int rx_budget; +}; + +/* Increment RX budget and schedule RX refill if necessary */ +static void mhi_wwan_rx_budget_inc(struct mhi_wwan_dev *mhiwwan) +{ + spin_lock(&mhiwwan->rx_lock); + + mhiwwan->rx_budget++; + + if (test_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags)) + schedule_work(&mhiwwan->rx_refill); + + spin_unlock(&mhiwwan->rx_lock); +} + +/* Decrement RX budget if non-zero and return true on success */ +static bool mhi_wwan_rx_budget_dec(struct mhi_wwan_dev *mhiwwan) +{ + bool ret = false; + + spin_lock(&mhiwwan->rx_lock); + + if (mhiwwan->rx_budget) + mhiwwan->rx_budget--; + + if (mhiwwan->rx_budget && test_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags)) + ret = true; + + spin_unlock(&mhiwwan->rx_lock); + + return ret; +} + +static void __mhi_skb_destructor(struct sk_buff *skb) +{ + /* RX buffer has been consumed, increase the allowed budget */ + mhi_wwan_rx_budget_inc(skb_shinfo(skb)->destructor_arg); +} + +static void mhi_wwan_ctrl_refill_work(struct work_struct *work) +{ + struct mhi_wwan_dev *mhiwwan = container_of(work, struct mhi_wwan_dev, rx_refill); + struct mhi_device *mhi_dev = mhiwwan->mhi_dev; + + while (mhi_wwan_rx_budget_dec(mhiwwan)) { + struct sk_buff *skb; + + skb = alloc_skb(mhiwwan->mtu, GFP_KERNEL); + if (!skb) { + mhi_wwan_rx_budget_inc(mhiwwan); + break; + } + + /* To prevent unlimited buffer allocation if nothing consumes + * the RX buffers (passed to WWAN core), track their lifespan + * to not allocate more than allowed budget. + */ + skb->destructor = __mhi_skb_destructor; + skb_shinfo(skb)->destructor_arg = mhiwwan; + + if (mhi_queue_skb(mhi_dev, DMA_FROM_DEVICE, skb, mhiwwan->mtu, MHI_EOT)) { + dev_err(&mhi_dev->dev, "Failed to queue buffer\n"); + kfree_skb(skb); + break; + } + } +} + +static int mhi_wwan_ctrl_start(struct wwan_port *port) +{ + struct mhi_wwan_dev *mhiwwan = wwan_port_get_drvdata(port); + int ret; + + /* Start mhi device's channel(s) */ + ret = mhi_prepare_for_transfer(mhiwwan->mhi_dev); + if (ret) + return ret; + + /* Don't allocate more buffers than MHI channel queue size */ + mhiwwan->rx_budget = mhi_get_free_desc_count(mhiwwan->mhi_dev, DMA_FROM_DEVICE); + + /* Add buffers to the MHI inbound queue */ + if (test_bit(MHI_WWAN_DL_CAP, &mhiwwan->flags)) { + set_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags); + mhi_wwan_ctrl_refill_work(&mhiwwan->rx_refill); + } + + return 0; +} + +static void mhi_wwan_ctrl_stop(struct wwan_port *port) +{ + struct mhi_wwan_dev *mhiwwan = wwan_port_get_drvdata(port); + + spin_lock(&mhiwwan->rx_lock); + clear_bit(MHI_WWAN_RX_REFILL, &mhiwwan->flags); + spin_unlock(&mhiwwan->rx_lock); + + cancel_work_sync(&mhiwwan->rx_refill); + + mhi_unprepare_from_transfer(mhiwwan->mhi_dev); +} + +static int mhi_wwan_ctrl_tx(struct wwan_port *port, struct sk_buff *skb) +{ + struct mhi_wwan_dev *mhiwwan = wwan_port_get_drvdata(port); + int ret; + + if (skb->len > mhiwwan->mtu) + return -EMSGSIZE; + + if (!test_bit(MHI_WWAN_UL_CAP, &mhiwwan->flags)) + return -EOPNOTSUPP; + + /* Queue the packet for MHI transfer and check fullness of the queue */ + spin_lock_bh(&mhiwwan->tx_lock); + ret = mhi_queue_skb(mhiwwan->mhi_dev, DMA_TO_DEVICE, skb, skb->len, MHI_EOT); + if (mhi_queue_is_full(mhiwwan->mhi_dev, DMA_TO_DEVICE)) + wwan_port_txoff(port); + spin_unlock_bh(&mhiwwan->tx_lock); + + return ret; +} + +static const struct wwan_port_ops wwan_pops = { + .start = mhi_wwan_ctrl_start, + .stop = mhi_wwan_ctrl_stop, + .tx = mhi_wwan_ctrl_tx, +}; + +static void mhi_ul_xfer_cb(struct mhi_device *mhi_dev, + struct mhi_result *mhi_result) +{ + struct mhi_wwan_dev *mhiwwan = dev_get_drvdata(&mhi_dev->dev); + struct wwan_port *port = mhiwwan->wwan_port; + struct sk_buff *skb = mhi_result->buf_addr; + + dev_dbg(&mhi_dev->dev, "%s: status: %d xfer_len: %zu\n", __func__, + mhi_result->transaction_status, mhi_result->bytes_xferd); + + /* MHI core has done with the buffer, release it */ + consume_skb(skb); + + /* There is likely new slot available in the MHI queue, re-allow TX */ + spin_lock_bh(&mhiwwan->tx_lock); + if (!mhi_queue_is_full(mhiwwan->mhi_dev, DMA_TO_DEVICE)) + wwan_port_txon(port); + spin_unlock_bh(&mhiwwan->tx_lock); +} + +static void mhi_dl_xfer_cb(struct mhi_device *mhi_dev, + struct mhi_result *mhi_result) +{ + struct mhi_wwan_dev *mhiwwan = dev_get_drvdata(&mhi_dev->dev); + struct wwan_port *port = mhiwwan->wwan_port; + struct sk_buff *skb = mhi_result->buf_addr; + + dev_dbg(&mhi_dev->dev, "%s: status: %d receive_len: %zu\n", __func__, + mhi_result->transaction_status, mhi_result->bytes_xferd); + + if (mhi_result->transaction_status && + mhi_result->transaction_status != -EOVERFLOW) { + kfree_skb(skb); + return; + } + + /* MHI core does not update skb->len, do it before forward */ + skb_put(skb, mhi_result->bytes_xferd); + wwan_port_rx(port, skb); + + /* Do not increment rx budget nor refill RX buffers now, wait for the + * buffer to be consumed. Done from __mhi_skb_destructor(). + */ +} + +static int mhi_wwan_ctrl_probe(struct mhi_device *mhi_dev, + const struct mhi_device_id *id) +{ + struct mhi_controller *cntrl = mhi_dev->mhi_cntrl; + struct mhi_wwan_dev *mhiwwan; + struct wwan_port *port; + + mhiwwan = kzalloc(sizeof(*mhiwwan), GFP_KERNEL); + if (!mhiwwan) + return -ENOMEM; + + mhiwwan->mhi_dev = mhi_dev; + mhiwwan->mtu = MHI_WWAN_MAX_MTU; + INIT_WORK(&mhiwwan->rx_refill, mhi_wwan_ctrl_refill_work); + spin_lock_init(&mhiwwan->tx_lock); + spin_lock_init(&mhiwwan->rx_lock); + + if (mhi_dev->dl_chan) + set_bit(MHI_WWAN_DL_CAP, &mhiwwan->flags); + if (mhi_dev->ul_chan) + set_bit(MHI_WWAN_UL_CAP, &mhiwwan->flags); + + dev_set_drvdata(&mhi_dev->dev, mhiwwan); + + /* Register as a wwan port, id->driver_data contains wwan port type */ + port = wwan_create_port(&cntrl->mhi_dev->dev, id->driver_data, + &wwan_pops, mhiwwan); + if (IS_ERR(port)) { + kfree(mhiwwan); + return PTR_ERR(port); + } + + mhiwwan->wwan_port = port; + + return 0; +}; + +static void mhi_wwan_ctrl_remove(struct mhi_device *mhi_dev) +{ + struct mhi_wwan_dev *mhiwwan = dev_get_drvdata(&mhi_dev->dev); + + wwan_remove_port(mhiwwan->wwan_port); + kfree(mhiwwan); +} + +static const struct mhi_device_id mhi_wwan_ctrl_match_table[] = { + { .chan = "DUN", .driver_data = WWAN_PORT_AT }, + { .chan = "MBIM", .driver_data = WWAN_PORT_MBIM }, + { .chan = "QMI", .driver_data = WWAN_PORT_QMI }, + { .chan = "DIAG", .driver_data = WWAN_PORT_QCDM }, + { .chan = "FIREHOSE", .driver_data = WWAN_PORT_FIREHOSE }, + {}, +}; +MODULE_DEVICE_TABLE(mhi, mhi_wwan_ctrl_match_table); + +static struct mhi_driver mhi_wwan_ctrl_driver = { + .id_table = mhi_wwan_ctrl_match_table, + .remove = mhi_wwan_ctrl_remove, + .probe = mhi_wwan_ctrl_probe, + .ul_xfer_cb = mhi_ul_xfer_cb, + .dl_xfer_cb = mhi_dl_xfer_cb, + .driver = { + .name = "mhi_wwan_ctrl", + }, +}; + +module_mhi_driver(mhi_wwan_ctrl_driver); + +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("MHI WWAN CTRL Driver"); +MODULE_AUTHOR("Loic Poulain ");