Re: [PATCH] bus: mhi: Add MHI PCI support

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Wed 23 Sep 08:40 CDT 2020, 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
> based PCIe modules. The MHI channels have been extracted from mhi
> downstream driver.
> 
> This driver is easily extendable to support other MHI PCI devices like
> different modem hw or OEM superset.
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> ---
[..]
> diff --git a/drivers/bus/mhi/controllers/mhi_pci_common.c b/drivers/bus/mhi/controllers/mhi_pci_common.c
> new file mode 100644
> index 0000000..705b283
> --- /dev/null
> +++ b/drivers/bus/mhi/controllers/mhi_pci_common.c

ath11k is also "PCI" and "MHI" but this isn't "common" code for it, so
perhaps "mhi_pci_generic.c" or "mhi_pci_modem.c"?

> @@ -0,0 +1,339 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * MHI PCI driver - MHI over PCI controller driver
> + *
> + * This module is a generic driver for registering pure 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>
> +#include <linux/delay.h>

Can you confirm that you need delay.h?

> +
> +#define MHI_PCI_BAR_NUM 0
> +
> +enum {
> +	EV_RING_0,
> +	EV_RING_1,
> +	EV_RING_2,
> +	EV_RING_3,

Maybe you can just use the numbers 0-3 instead?

> +};
> +
[..]
> +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);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to assign pci resource: %d\n", err);

Afaict all code paths of pci_assign_resource() will log already.

> +		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));
> +	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_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);
> +
> +	mhic = devm_kzalloc(&pdev->dev, sizeof(*mhic), GFP_KERNEL);
> +	if (!mhic) {
> +		dev_err(&pdev->dev, "failed to allocate mhi controller\n");

kzalloc() will log errors as well.

> +		return -ENOMEM;
> +	}
> +
> +	mhic_config = info->config;
> +	mhic->cntrl_dev = &pdev->dev;
> +	mhic->iova_start = 0;
> +	mhic->iova_stop = 0xffffffff;
> +	mhic->fw_image = NULL;
> +	mhic->edl_image = NULL;
> +
> +	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) {
> +		dev_err(&pdev->dev, "failed to register MHI controller\n");

Afaict all errors that occurs if you pass valid data to this function
will print an error message already...

> +		pci_free_irq_vectors(pdev);
> +		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");

mhi_unregister_controller()?

> +		return err;
> +	}
> +
> +	err = mhi_sync_power_up(mhic);
> +	if (err) {
> +		dev_err(&pdev->dev, "failed to power up MHI controller\n");
> +		mhi_unprepare_after_power_down(mhic);
> +		mhi_unregister_controller(mhic);
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static void mhi_pci_remove(struct pci_dev *pdev)
> +{
> +	struct mhi_controller *mhic = pci_get_drvdata(pdev);
> +
> +	mhi_power_down(mhic, true);
> +	mhi_unprepare_after_power_down(mhic);
> +	mhi_unregister_controller(mhic);
> +}
> +
> +static struct pci_driver mhi_pci_driver = {
> +	.name		= "mhi-pci",
> +	.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("mhi-pci");

Please expand this

> +MODULE_LICENSE("GPL");
> +MODULE_VERSION("1");

And please drop the version, as this is likely not going to be updated
consistently.

Regards,
Bjorn