Re: [PATCH V13 10/10] vfio, platform: add QTI HIDMA reset driver

[Eric Auger <eric.auger@linaro.org>]

Hi Sinan,
On 01/29/2016 11:35 PM, Sinan Kaya wrote:
> In situations where the userspace driver is stopped abnormally and the
> VFIO platform device is released, the assigned HW device currently is
> left running. As a consequence the HW device might continue issuing IRQs
> and performing DMA accesses.
> 
> This patch is implementing a reset driver for HIDMA platform driver.
> This gets called by the VFIO platform reset interface.
> 
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
>  drivers/vfio/platform/reset/Kconfig                |  9 ++
>  drivers/vfio/platform/reset/Makefile               |  2 +
>  .../vfio/platform/reset/vfio_platform_qcomhidma.c  | 99 ++++++++++++++++++++++
>  3 files changed, 110 insertions(+)
>  create mode 100644 drivers/vfio/platform/reset/vfio_platform_qcomhidma.c
> 
> diff --git a/drivers/vfio/platform/reset/Kconfig b/drivers/vfio/platform/reset/Kconfig
> index 70cccc5..d02b3b5 100644
> --- a/drivers/vfio/platform/reset/Kconfig
> +++ b/drivers/vfio/platform/reset/Kconfig
> @@ -13,3 +13,12 @@ config VFIO_PLATFORM_AMDXGBE_RESET
>  	  Enables the VFIO platform driver to handle reset for AMD XGBE
>  
>  	  If you don't know what to do here, say N.
> +
> +config VFIO_PLATFORM_QCOMHIDMA_RESET
> +	tristate "VFIO support for Qualcomm Technologies HIDMA reset"
> +	depends on VFIO_PLATFORM
> +	help
> +	  Enables the VFIO platform driver to handle reset for Qualcomm Technologies
> +	  HIDMA Channel.
> +
> +	  If you don't know what to do here, say N.
> diff --git a/drivers/vfio/platform/reset/Makefile b/drivers/vfio/platform/reset/Makefile
> index 93f4e23..ec7748a 100644
> --- a/drivers/vfio/platform/reset/Makefile
> +++ b/drivers/vfio/platform/reset/Makefile
> @@ -1,7 +1,9 @@
>  vfio-platform-calxedaxgmac-y := vfio_platform_calxedaxgmac.o
>  vfio-platform-amdxgbe-y := vfio_platform_amdxgbe.o
> +vfio-platform-qcomhidma-y := vfio_platform_qcomhidma.o
>  
>  ccflags-y += -Idrivers/vfio/platform
>  
>  obj-$(CONFIG_VFIO_PLATFORM_CALXEDAXGMAC_RESET) += vfio-platform-calxedaxgmac.o
> +obj-$(CONFIG_VFIO_PLATFORM_QCOMHIDMA_RESET) += vfio-platform-qcomhidma.o
>  obj-$(CONFIG_VFIO_PLATFORM_AMDXGBE_RESET) += vfio-platform-amdxgbe.o
> diff --git a/drivers/vfio/platform/reset/vfio_platform_qcomhidma.c b/drivers/vfio/platform/reset/vfio_platform_qcomhidma.c
> new file mode 100644
> index 0000000..4e7a59c
> --- /dev/null
> +++ b/drivers/vfio/platform/reset/vfio_platform_qcomhidma.c
> @@ -0,0 +1,99 @@
> +/*
> + * Qualcomm Technologies HIDMA VFIO Reset Driver
> + *
> + * Copyright (c) 2016, The Linux Foundation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/device.h>
> +#include <linux/iopoll.h>
> +
> +#include "vfio_platform_private.h"
> +
> +#define TRCA_CTRLSTS_OFFSET		0x000
> +#define EVCA_CTRLSTS_OFFSET		0x000
> +
> +#define CH_CONTROL_MASK		GENMASK(7, 0)
> +#define CH_STATE_MASK			GENMASK(7, 0)
> +#define CH_STATE_BIT_POS		0x8
> +
> +#define HIDMA_CH_STATE(val)	\
> +	((val >> CH_STATE_BIT_POS) & CH_STATE_MASK)
> +
> +#define EVCA_IRQ_EN_OFFSET		0x110
> +
> +#define CH_RESET			9
> +#define CH_DISABLED			0
> +
> +int vfio_platform_qcomhidma_reset(struct vfio_platform_device *vdev)
> +{
> +	struct vfio_platform_region trreg;
> +	struct vfio_platform_region evreg;
> +	u32 val;
> +	int ret;
> +
> +	if (vdev->num_regions != 2)
> +		return -ENODEV;
> +
> +	trreg = vdev->regions[0];
> +	if (!trreg.ioaddr) {
> +		trreg.ioaddr =
> +			ioremap_nocache(trreg.addr, trreg.size);
this is going to leak. See "vfio: platform: reset: calxedaxgmac: fix
ioaddr leak".
> +		if (!trreg.ioaddr)
> +			return -ENOMEM;
> +	}
> +
> +	evreg = vdev->regions[1];
> +	if (!evreg.ioaddr) {
> +		evreg.ioaddr =
> +			ioremap_nocache(evreg.addr, evreg.size);
same here
> +		if (!evreg.ioaddr)
> +			return -ENOMEM;
> +	}
> +
I understood the device is a kind of SR-IOV platform device. When the VF
gets reset are there any interactions with the management driver? Is it
handled by HW?

Best Regards

Eric
> +	/* disable IRQ */
> +	writel(0, evreg.ioaddr + EVCA_IRQ_EN_OFFSET);
> +
> +	/* reset both transfer and event channels */
> +	val = readl(trreg.ioaddr + TRCA_CTRLSTS_OFFSET);
> +	val &= ~(CH_CONTROL_MASK << 16);
> +	val |= CH_RESET << 16;
> +	writel(val, trreg.ioaddr + TRCA_CTRLSTS_OFFSET);
> +
> +	ret = readl_poll_timeout(trreg.ioaddr + TRCA_CTRLSTS_OFFSET, val,
> +				 HIDMA_CH_STATE(val) == CH_DISABLED, 1000,
> +				 10000);
> +	if (ret)
> +		return ret;
> +
> +	val = readl(evreg.ioaddr + EVCA_CTRLSTS_OFFSET);
> +	val &= ~(CH_CONTROL_MASK << 16);
> +	val |= CH_RESET << 16;
> +	writel(val, evreg.ioaddr + EVCA_CTRLSTS_OFFSET);
> +
> +	ret = readl_poll_timeout(evreg.ioaddr + EVCA_CTRLSTS_OFFSET, val,
> +				 HIDMA_CH_STATE(val) == CH_DISABLED, 1000,
> +				 10000);
> +	if (ret)
> +		return ret;
> +
> +	pr_info("HIDMA channel reset\n");
> +	return 0;
> +}
> +module_vfio_reset_handler("qcom,hidma", NULL,
> +			  vfio_platform_qcomhidma_reset);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Reset support for Qualcomm Technologies HIDMA device");
>