VFIO: platform: reset: AMD xgbe reset module

This patch introduces a module that registers and implements a low-level
reset function for the AMD XGBE device.

it performs the following actions:
- reset the PHY
- disable auto-negotiation
- disable & clear auto-negotiation IRQ
- soft-reset the MAC

Those tiny pieces of code are inherited from the native xgbe driver.
Signed-off-by: Eric Auger <eric.auger@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/platform/reset/Kconfig

@@ -5,3 +5,11 @@ config VFIO_PLATFORM_CALXEDAXGMAC_RESET
 	  Enables the VFIO platform driver to handle reset for Calxeda xgmac
 
 	  If you don't know what to do here, say N.
+
+config VFIO_PLATFORM_AMDXGBE_RESET
+	tristate "VFIO support for AMD XGBE reset"
+	depends on VFIO_PLATFORM
+	help
+	  Enables the VFIO platform driver to handle reset for AMD XGBE
+
+	  If you don't know what to do here, say N.

drivers/vfio/platform/reset/Makefile

 vfio-platform-calxedaxgmac-y := vfio_platform_calxedaxgmac.o
+vfio-platform-amdxgbe-y := vfio_platform_amdxgbe.o
 
 ccflags-y += -Idrivers/vfio/platform
 
 obj-$(CONFIG_VFIO_PLATFORM_CALXEDAXGMAC_RESET) += vfio-platform-calxedaxgmac.o
+obj-$(CONFIG_VFIO_PLATFORM_AMDXGBE_RESET) += vfio-platform-amdxgbe.o

drivers/vfio/platform/reset/vfio_platform_amdxgbe.c

+/*
+ * VFIO platform driver specialized for AMD xgbe reset
+ * reset code is inherited from AMD xgbe native driver
+ *
+ * Copyright (c) 2015 Linaro Ltd.
+ *              www.linaro.org
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <uapi/linux/mdio.h>
+#include <linux/delay.h>
+
+#include "vfio_platform_private.h"
+
+#define DMA_MR			0x3000
+#define MAC_VR			0x0110
+#define DMA_ISR			0x3008
+#define MAC_ISR			0x00b0
+#define PCS_MMD_SELECT		0xff
+#define MDIO_AN_INT		0x8002
+#define MDIO_AN_INTMASK		0x8001
+
+static unsigned int xmdio_read(void *ioaddr, unsigned int mmd,
+			       unsigned int reg)
+{
+	unsigned int mmd_address, value;
+
+	mmd_address = (mmd << 16) | ((reg) & 0xffff);
+	iowrite32(mmd_address >> 8, ioaddr + (PCS_MMD_SELECT << 2));
+	value = ioread32(ioaddr + ((mmd_address & 0xff) << 2));
+	return value;
+}
+
+static void xmdio_write(void *ioaddr, unsigned int mmd,
+			unsigned int reg, unsigned int value)
+{
+	unsigned int mmd_address;
+
+	mmd_address = (mmd << 16) | ((reg) & 0xffff);
+	iowrite32(mmd_address >> 8, ioaddr + (PCS_MMD_SELECT << 2));
+	iowrite32(value, ioaddr + ((mmd_address & 0xff) << 2));
+}
+
+int vfio_platform_amdxgbe_reset(struct vfio_platform_device *vdev)
+{
+	struct vfio_platform_region *xgmac_regs = &vdev->regions[0];
+	struct vfio_platform_region *xpcs_regs = &vdev->regions[1];
+	u32 dma_mr_value, pcs_value, value;
+	unsigned int count;
+
+	if (!xgmac_regs->ioaddr) {
+		xgmac_regs->ioaddr =
+			ioremap_nocache(xgmac_regs->addr, xgmac_regs->size);
+		if (!xgmac_regs->ioaddr)
+			return -ENOMEM;
+	}
+	if (!xpcs_regs->ioaddr) {
+		xpcs_regs->ioaddr =
+			ioremap_nocache(xpcs_regs->addr, xpcs_regs->size);
+		if (!xpcs_regs->ioaddr)
+			return -ENOMEM;
+	}
+
+	/* reset the PHY through MDIO*/
+	pcs_value = xmdio_read(xpcs_regs->ioaddr, MDIO_MMD_PCS, MDIO_CTRL1);
+	pcs_value |= MDIO_CTRL1_RESET;
+	xmdio_write(xpcs_regs->ioaddr, MDIO_MMD_PCS, MDIO_CTRL1, pcs_value);
+
+	count = 50;
+	do {
+		msleep(20);
+		pcs_value = xmdio_read(xpcs_regs->ioaddr, MDIO_MMD_PCS,
+					MDIO_CTRL1);
+	} while ((pcs_value & MDIO_CTRL1_RESET) && --count);
+
+	if (pcs_value & MDIO_CTRL1_RESET)
+		pr_warn("%s XGBE PHY reset timeout\n", __func__);
+
+	/* disable auto-negotiation */
+	value = xmdio_read(xpcs_regs->ioaddr, MDIO_MMD_AN, MDIO_CTRL1);
+	value &= ~MDIO_AN_CTRL1_ENABLE;
+	xmdio_write(xpcs_regs->ioaddr, MDIO_MMD_AN, MDIO_CTRL1, value);
+
+	/* disable AN IRQ */
+	xmdio_write(xpcs_regs->ioaddr, MDIO_MMD_AN, MDIO_AN_INTMASK, 0);
+
+	/* clear AN IRQ */
+	xmdio_write(xpcs_regs->ioaddr, MDIO_MMD_AN, MDIO_AN_INT, 0);
+
+	/* MAC software reset */
+	dma_mr_value = ioread32(xgmac_regs->ioaddr + DMA_MR);
+	dma_mr_value |= 0x1;
+	iowrite32(dma_mr_value, xgmac_regs->ioaddr + DMA_MR);
+
+	usleep_range(10, 15);
+
+	count = 2000;
+	while (count-- && (ioread32(xgmac_regs->ioaddr + DMA_MR) & 1))
+		usleep_range(500, 600);
+
+	if (!count)
+		pr_warn("%s MAC SW reset failed\n", __func__);
+
+	return 0;
+}
+
+module_vfio_reset_handler("amd,xgbe-seattle-v1a", vfio_platform_amdxgbe_reset);
+
+MODULE_VERSION("0.1");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Eric Auger <eric.auger@linaro.org>");
+MODULE_DESCRIPTION("Reset support for AMD xgbe vfio platform device");