Re: [PATCH v3] bus: mhi: Add MHI PCI support for WWAN modems

[Bhaumik Bhatt <bbhatt@codeaurora.org>]

On 2020-10-06 07:54, Loic Poulain wrote:
> This is a generic MHI-over-PCI controller driver for MHI only devices
> such as QCOM modems. For now it supports registering of Qualcomm SDX55
For now, it supports registration of...
> based PCIe modules. The MHI channels have been extracted from mhi
MHI (in all caps) or just use "the" instead
> downstream driver.
> 
> This driver is for MHI-only devices which have all functionnalities
functionalities
> exposed through MHI channels and accessed by the corresponding MHI
> device drivers (no out-of-band communication).
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> ---
>  v2: - remove useless delay.h include
>      - remove over-logging on error
>      - remove controller subdir
>      - rename to mhi_pci_modem.c
>      - Fix mhi_pci_probe exit path on error
>      - expand module description
>      - drop module version
>  v3: - Rename to mhi_pci_generic
>      - Add hardware accelerated IP channel (IPA)
>      - Added fw/edl names for sdx55m
> 
>  drivers/bus/mhi/Kconfig           |   9 ++
>  drivers/bus/mhi/Makefile          |   3 +
>  drivers/bus/mhi/mhi_pci_generic.c | 332 
> ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 344 insertions(+)
>  create mode 100644 drivers/bus/mhi/mhi_pci_generic.c
> 
> diff --git a/drivers/bus/mhi/Kconfig b/drivers/bus/mhi/Kconfig
> index e841c10..daa8528 100644
> --- a/drivers/bus/mhi/Kconfig
> +++ b/drivers/bus/mhi/Kconfig
> @@ -20,3 +20,12 @@ config MHI_BUS_DEBUG
>  	  Enable debugfs support for use with the MHI transport. Allows
>  	  reading and/or modifying some values within the MHI controller
>  	  for debug and test purposes.
> +
> +config MHI_BUS_PCI_GENERIC
> +	tristate "MHI PCI controller driver"
> +	depends on MHI_BUS
> +	depends on PCI
> +	help
> +	  This driver provides Modem Host Interface (MHI) PCI controller 
> driver
> +	  for devices such as Qualcomm SDX55 based PCIe modems.
> +
> diff --git a/drivers/bus/mhi/Makefile b/drivers/bus/mhi/Makefile
> index 19e6443..d1a4ef3 100644
> --- a/drivers/bus/mhi/Makefile
> +++ b/drivers/bus/mhi/Makefile
> @@ -1,2 +1,5 @@
>  # core layer
>  obj-y += core/
> +
> +obj-$(CONFIG_MHI_BUS_PCI_GENERIC) := mhi_pci_generic.o
> +
> diff --git a/drivers/bus/mhi/mhi_pci_generic.c
> b/drivers/bus/mhi/mhi_pci_generic.c
> new file mode 100644
> index 0000000..03fcf76
> --- /dev/null
> +++ b/drivers/bus/mhi/mhi_pci_generic.c
> @@ -0,0 +1,332 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * MHI PCI driver - MHI over PCI controller driver
> + *
> + * This module is a generic driver for registering MHI-over-PCI 
> devices,
> + * such as PCIe QCOM modems.
> + *
> + * Copyright (C) 2020 Linaro Ltd <loic.poulain@linaro.org>
> + */
> +
> +#include <linux/device.h>
> +#include <linux/mhi.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +
> +#define MHI_PCI_BAR_NUM 0
> +
> +struct mhi_pci_dev_info {
> +	const struct mhi_controller_config *config;
> +	const char *name;
> +	const char *fw;
> +	const char *edl;
> +};
> +
> +#define MHI_CHANNEL_CONFIG_TX(cnum, cname, elems, event)	\
> +	{							\
> +		.num = cnum,					\
> +		.name = cname,					\
> +		.num_elements = elems,				\
> +		.event_ring = event,				\
> +		.dir = DMA_TO_DEVICE,				\
> +		.ee_mask = BIT(MHI_EE_AMSS),			\
> +		.pollcfg = 0,					\
> +		.doorbell = MHI_DB_BRST_DISABLE,		\
> +		.lpm_notify = false,				\
> +		.offload_channel = false,			\
> +		.doorbell_mode_switch = false,			\
> +	}							\
> +
> +#define MHI_CHANNEL_CONFIG_RX(cnum, cname, elems, event)	\
> +	{							\
> +		.num = cnum,					\
> +		.name = cname,					\
> +		.num_elements = elems,				\
> +		.event_ring = event,				\
> +		.dir = DMA_FROM_DEVICE,				\
> +		.ee_mask = BIT(MHI_EE_AMSS),			\
> +		.pollcfg = 0,					\
> +		.doorbell = MHI_DB_BRST_DISABLE,		\
> +		.lpm_notify = false,				\
> +		.offload_channel = false,			\
> +		.doorbell_mode_switch = false,			\
> +	}
> +
> +#define MHI_EVENT_CONFIG_CTRL(enum)		\
> +	{					\
> +		.num_elements = 64,		\
> +		.irq_moderation_ms = 5,		\
> +		.irq = enum,			\
> +		.priority = 1,			\
> +		.mode = MHI_DB_BRST_DISABLE,	\
> +		.data_type = MHI_ER_CTRL,	\
> +		.hardware_event = false,	\
> +		.client_managed = false,	\
> +		.offload_channel = false,	\
> +	}
> +
> +#define MHI_EVENT_CONFIG_DATA(enum)		\
> +	{					\
> +		.num_elements = 64,		\
> +		.irq_moderation_ms = 5,		\
> +		.irq = enum,			\
> +		.priority = 1,			\
> +		.mode = MHI_DB_BRST_DISABLE,	\
> +		.data_type = MHI_ER_DATA,	\
> +		.hardware_event = false,	\
> +		.client_managed = false,	\
> +		.offload_channel = false,	\
> +	}
> +
> +#define MHI_EVENT_CONFIG_HW_DATA(enum, cnum)	\
> +	{					\
> +		.num_elements = 64,		\
> +		.irq_moderation_ms = 5,		\
> +		.irq = enum,			\
> +		.priority = 1,			\
> +		.mode = MHI_DB_BRST_ENABLE,	\
> +		.data_type = MHI_ER_DATA,	\
> +		.hardware_event = true,		\
> +		.client_managed = false,	\
> +		.offload_channel = false,	\
> +		.channel = cnum,		\
> +	}
> +
> +static const struct mhi_channel_config modem_qcom_v1_mhi_channels[] = 
> {
> +	MHI_CHANNEL_CONFIG_TX(12, "MBIM", 4, 0),
> +	MHI_CHANNEL_CONFIG_RX(13, "MBIM", 4, 0),
> +	MHI_CHANNEL_CONFIG_TX(14, "QMI", 4, 0),
> +	MHI_CHANNEL_CONFIG_RX(15, "QMI", 4, 0),
> +	MHI_CHANNEL_CONFIG_TX(20, "IPCR", 4, 0),
> +	MHI_CHANNEL_CONFIG_RX(21, "IPCR", 4, 0),
> +	MHI_CHANNEL_CONFIG_TX(100, "IP_HW0", 64, 1),
> +	MHI_CHANNEL_CONFIG_RX(101, "IP_HW0", 64, 2),
> +};
> +
> +static const struct mhi_event_config modem_qcom_v1_mhi_events[] = {
> +	/* first ring is control+data ring */
> +	MHI_EVENT_CONFIG_CTRL(0),
> +	/* Hardware channels request dedicated hardware event rings */
> +	MHI_EVENT_CONFIG_HW_DATA(1, 100),
> +	MHI_EVENT_CONFIG_HW_DATA(2, 101)
> +};
> +
> +static const struct mhi_controller_config modem_qcom_v1_mhi_config = {
> +	.max_channels = 128,
> +	.timeout_ms = 5000,
> +	.num_channels = ARRAY_SIZE(modem_qcom_v1_mhi_channels),
> +	.ch_cfg = modem_qcom_v1_mhi_channels,
> +	.num_events = ARRAY_SIZE(modem_qcom_v1_mhi_events),
> +	.event_cfg = modem_qcom_v1_mhi_events,
> +};
> +
> +static const struct mhi_pci_dev_info mhi_qcom_sdx55_info = {
> +	.name = "qcom-sdx55m",
> +	.fw = "qcom/sdx55m/sbl1.mbn",
> +	.edl = "qcom/sdx55m/edl.mbn",
> +	.config = &modem_qcom_v1_mhi_config
> +};
> +
> +static const struct pci_device_id mhi_pci_id_table[] = {
> +	{ PCI_DEVICE(PCI_VENDOR_ID_QCOM, 0x0306),
> +		.driver_data = (kernel_ulong_t) &mhi_qcom_sdx55_info },
> +	{  }
> +};
> +MODULE_DEVICE_TABLE(pci, mhi_pci_id_table);
> +
> +static int mhi_pci_read_reg(struct mhi_controller *mhic, void __iomem 
> *addr,
> +			    u32 *out)
> +{
> +	*out = readl(addr);
> +	return 0;
> +}
> +
> +static void mhi_pci_write_reg(struct mhi_controller *mhic, void 
> __iomem *addr,
> +			      u32 val)
> +{
> +	writel(val, addr);
> +}
> +
> +static void mhi_pci_status_cb(struct mhi_controller *mhi_cntrl,
> +			      enum mhi_callback cb)
> +{
> +	return;
> +}
> +
> +static int mhi_pci_claim(struct mhi_controller *mhic)
> +{
> +	struct pci_dev *pdev = to_pci_dev(mhic->cntrl_dev);
> +	int err;
> +
> +	err = pci_assign_resource(pdev, MHI_PCI_BAR_NUM);
Can MHI_PCI_BAR_NUM be a parameter to this function instead of 
hardcoding it to 0?
> +	if (err)
> +		return err;
> +
> +	err = pcim_enable_device(pdev);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to enable pci device: %d\n", err);
> +		return err;
> +	}
> +
> +	err = pcim_iomap_regions(pdev, 1 << MHI_PCI_BAR_NUM, pci_name(pdev));
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to map pci region: %d\n", err);
> +		return err;
> +	}
> +	mhic->regs = pcim_iomap_table(pdev)[MHI_PCI_BAR_NUM];
> +
> +	err = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
Some controllers may need a 64 bit mask. Can that be added as a 
parameter to this
function?
> +	if (err) {
> +		dev_err(&pdev->dev, "Cannot set proper DMA mask\n");
> +		return err;
> +	}
> +
> +	err = pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(32));
> +	if (err) {
> +		dev_err(&pdev->dev, "set consistent dma mask failed\n");
> +		return err;
> +	}
> +
> +	pci_set_master(pdev);
> +
> +	return 0;
> +}
> +
> +static int mhi_pci_get_irqs(struct mhi_controller *mhic,
> +			    const struct mhi_controller_config *mhic_config)
> +{
> +	struct pci_dev *pdev = to_pci_dev(mhic->cntrl_dev);
> +	int num_vectors, i;
> +	int *irq;
> +
> +	/*
> +	 * Alloc one MSI vector per event ring, ideally...
> +	 * No explicit pci_free_irq_vectors required, done by pcim_release
> +	 */
> +	num_vectors = pci_alloc_irq_vectors(pdev, 1, mhic_config->num_events,
> +					    PCI_IRQ_MSI);
> +	if (num_vectors < 0) {
> +		dev_err(&pdev->dev, "Error allocating MSI vectors %d\n",
> +			num_vectors);
> +		return num_vectors;
> +	}
> +
> +	if (num_vectors < mhic_config->num_events) {
> +		dev_warn(&pdev->dev, "Not enough MSI vectors (%d/%d)\n",
> +			 num_vectors, mhic_config->num_events);
> +		/* use shared IRQ */
> +	}
> +
> +	irq = devm_kcalloc(&pdev->dev, mhic_config->num_events, sizeof(int),
> +			   GFP_KERNEL);
> +	if (!irq)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < mhic_config->num_events; i++) {
> +		int vector = i >= num_vectors ? (num_vectors - 1) : i;
> +
> +		irq[i] = pci_irq_vector(pdev, vector);
> +	}
> +
> +	mhic->irq = irq;
> +	mhic->nr_irqs = mhic_config->num_events;
> +
> +	return 0;
> +}
> +
> +static int mhi_pci_runtime_get(struct mhi_controller *mhi_cntrl)
> +{
> +	/* no PM for now */
> +	return 0;
> +}
> +
> +static void mhi_pci_runtime_put(struct mhi_controller *mhi_cntrl)
> +{
> +	/* no PM for now */
> +	return;
> +}
> +
> +static int mhi_pci_probe(struct pci_dev *pdev, const struct 
> pci_device_id *id)
> +{
> +	const struct mhi_pci_dev_info *info = (struct mhi_pci_dev_info *)
> id->driver_data;
> +	const struct mhi_controller_config *mhic_config;
> +	struct mhi_controller *mhic;
> +	int err;
> +
> +	dev_info(&pdev->dev, "MHI PCI device found: %s\n", info->name);
Can DMA_BIT_MASK and MHI_PCI_BAR_NUM be made present in mhi_pci_dev_info 
for
different clients and passed down to the mhi_pci_claim() function to 
make it
more configurable/extensible for different root ports and memory 
requirements?
> +
> +	mhic = devm_kzalloc(&pdev->dev, sizeof(*mhic), GFP_KERNEL);
> +	if (!mhic)
> +		return -ENOMEM;
> +
> +	mhic_config = info->config;
> +	mhic->cntrl_dev = &pdev->dev;
> +	mhic->iova_start = 0;
> +	mhic->iova_stop = 0xffffffff;
> +	mhic->fw_image = info->fw;
> +	mhic->edl_image = info->edl;
> +
> +	mhic->read_reg = mhi_pci_read_reg;
> +	mhic->write_reg = mhi_pci_write_reg;
> +	mhic->status_cb = mhi_pci_status_cb;
> +	mhic->runtime_get = mhi_pci_runtime_get;
> +	mhic->runtime_put = mhi_pci_runtime_put;
> +
> +	err = mhi_pci_claim(mhic);
> +	if (err)
> +		return err;
> +
> +	err = mhi_pci_get_irqs(mhic, mhic_config);
> +	if (err)
> +		return err;
> +
> +	pci_set_drvdata(pdev, mhic);
> +
> +	err = mhi_register_controller(mhic, mhic_config);
> +	if (err)
> +		return err;
> +
> +	/* MHI bus does not power up the controller by default */
> +	err = mhi_prepare_for_power_up(mhic);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to prepare MHI controller\n");
> +		goto err_unregister;
> +	}
> +
> +	err = mhi_sync_power_up(mhic);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to power up MHI controller\n");
> +		goto err_unprepare;
> +	}
> +
> +	return 0;
> +
> +err_unprepare:
> +	mhi_unprepare_after_power_down(mhic);
> +
> +err_unregister:
> +	mhi_unregister_controller(mhic);
> +
> +	return err;
> +}
> +
> +static void mhi_pci_remove(struct pci_dev *pdev)
> +{
> +	struct mhi_controller *mhic = pci_get_drvdata(pdev);
> +
> +	mhi_power_down(mhic, false);
> +	mhi_unprepare_after_power_down(mhic);
> +	mhi_unregister_controller(mhic);
> +}
> +
> +static struct pci_driver mhi_pci_driver = {
> +	.name		= "mhi-pci-generic",
> +	.id_table	= mhi_pci_id_table,
> +	.probe		= mhi_pci_probe,
> +	.remove		= mhi_pci_remove
> +};
> +module_pci_driver(mhi_pci_driver);
> +
> +MODULE_AUTHOR("Loic Poulain <loic.poulain@linaro,org>");
> +MODULE_DESCRIPTION("Modem Host Interface (MHI) PCI controller 
> driver");
> +MODULE_LICENSE("GPL");

Thanks,
Bhaumik
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