text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * aspeed-vhub -- Driver for Aspeed SoC "vHub" USB gadget
   *
   * core.c - Top level support
   *
   * Copyright 2017 IBM Corporation
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/delay.h>
  #include <linux/ioport.h>
  #include <linux/slab.h>
  #include <linux/errno.h>
  #include <linux/list.h>
  #include <linux/interrupt.h>
  #include <linux/proc_fs.h>
  #include <linux/prefetch.h>
  #include <linux/clk.h>
  #include <linux/usb/gadget.h>
  #include <linux/of.h>
  #include <linux/of_gpio.h>
  #include <linux/regmap.h>
  #include <linux/dma-mapping.h>
  
  #include "vhub.h"
  
  void ast_vhub_done(struct ast_vhub_ep *ep, struct ast_vhub_req *req,
  		   int status)
  {
  	bool internal = req->internal;
  
  	EPVDBG(ep, "completing request @%p, status %d\n", req, status);
  
  	list_del_init(&req->queue);
  
  	if (req->req.status == -EINPROGRESS)
  		req->req.status = status;
  
  	if (req->req.dma) {
  		if (!WARN_ON(!ep->dev))
  			usb_gadget_unmap_request(&ep->dev->gadget,
  						 &req->req, ep->epn.is_in);
  		req->req.dma = 0;
  	}
  
  	/*
  	 * If this isn't an internal EP0 request, call the core
  	 * to call the gadget completion.
  	 */
  	if (!internal) {
  		spin_unlock(&ep->vhub->lock);
  		usb_gadget_giveback_request(&ep->ep, &req->req);
  		spin_lock(&ep->vhub->lock);
  	}
  }
  
  void ast_vhub_nuke(struct ast_vhub_ep *ep, int status)
  {
  	struct ast_vhub_req *req;
  	int count = 0;
  
  	/* Beware, lock will be dropped & req-acquired by done() */
  	while (!list_empty(&ep->queue)) {
  		req = list_first_entry(&ep->queue, struct ast_vhub_req, queue);
  		ast_vhub_done(ep, req, status);
  		count++;
  	}
  	if (count)
  		EPDBG(ep, "Nuked %d request(s)\n", count);
  }
  
  struct usb_request *ast_vhub_alloc_request(struct usb_ep *u_ep,
  					   gfp_t gfp_flags)
  {
  	struct ast_vhub_req *req;
  
  	req = kzalloc(sizeof(*req), gfp_flags);
  	if (!req)
  		return NULL;
  	return &req->req;
  }
  
  void ast_vhub_free_request(struct usb_ep *u_ep, struct usb_request *u_req)
  {
  	struct ast_vhub_req *req = to_ast_req(u_req);
  
  	kfree(req);
  }
  
  static irqreturn_t ast_vhub_irq(int irq, void *data)
  {
  	struct ast_vhub *vhub = data;
  	irqreturn_t iret = IRQ_NONE;
  	u32 i, istat;
  
  	/* Stale interrupt while tearing down */
  	if (!vhub->ep0_bufs)
  		return IRQ_NONE;
  
  	spin_lock(&vhub->lock);
  
  	/* Read and ACK interrupts */
  	istat = readl(vhub->regs + AST_VHUB_ISR);
  	if (!istat)
  		goto bail;
  	writel(istat, vhub->regs + AST_VHUB_ISR);
  	iret = IRQ_HANDLED;
  
  	UDCVDBG(vhub, "irq status=%08x, ep_acks=%08x ep_nacks=%08x\n",
  	       istat,
  	       readl(vhub->regs + AST_VHUB_EP_ACK_ISR),
  	       readl(vhub->regs + AST_VHUB_EP_NACK_ISR));
  
  	/* Handle generic EPs first */
  	if (istat & VHUB_IRQ_EP_POOL_ACK_STALL) {
  		u32 ep_acks = readl(vhub->regs + AST_VHUB_EP_ACK_ISR);
  		writel(ep_acks, vhub->regs + AST_VHUB_EP_ACK_ISR);
  
  		for (i = 0; ep_acks && i < vhub->max_epns; i++) {
  			u32 mask = VHUB_EP_IRQ(i);
  			if (ep_acks & mask) {
  				ast_vhub_epn_ack_irq(&vhub->epns[i]);
  				ep_acks &= ~mask;
  			}
  		}
  	}
  
  	/* Handle device interrupts */
  	if (istat & vhub->port_irq_mask) {
  		unsigned long bitmap = istat;
  		int offset = VHUB_IRQ_DEV1_BIT;
  		int size = VHUB_IRQ_DEV1_BIT + vhub->max_ports;
  
  		for_each_set_bit_from(offset, &bitmap, size) {
  			i = offset - VHUB_IRQ_DEV1_BIT;
  			ast_vhub_dev_irq(&vhub->ports[i].dev);
  		}
  	}
  
  	/* Handle top-level vHub EP0 interrupts */
  	if (istat & (VHUB_IRQ_HUB_EP0_OUT_ACK_STALL |
  		     VHUB_IRQ_HUB_EP0_IN_ACK_STALL |
  		     VHUB_IRQ_HUB_EP0_SETUP)) {
  		if (istat & VHUB_IRQ_HUB_EP0_IN_ACK_STALL)
  			ast_vhub_ep0_handle_ack(&vhub->ep0, true);
  		if (istat & VHUB_IRQ_HUB_EP0_OUT_ACK_STALL)
  			ast_vhub_ep0_handle_ack(&vhub->ep0, false);
  		if (istat & VHUB_IRQ_HUB_EP0_SETUP)
  			ast_vhub_ep0_handle_setup(&vhub->ep0);
  	}
  
  	/* Various top level bus events */
  	if (istat & (VHUB_IRQ_BUS_RESUME |
  		     VHUB_IRQ_BUS_SUSPEND |
  		     VHUB_IRQ_BUS_RESET)) {
  		if (istat & VHUB_IRQ_BUS_RESUME)
  			ast_vhub_hub_resume(vhub);
  		if (istat & VHUB_IRQ_BUS_SUSPEND)
  			ast_vhub_hub_suspend(vhub);
  		if (istat & VHUB_IRQ_BUS_RESET)
  			ast_vhub_hub_reset(vhub);
  	}
  
   bail:
  	spin_unlock(&vhub->lock);
  	return iret;
  }
  
  void ast_vhub_init_hw(struct ast_vhub *vhub)
  {
  	u32 ctrl, port_mask, epn_mask;
  
  	UDCDBG(vhub,"(Re)Starting HW ...\n");
  
  	/* Enable PHY */
  	ctrl = VHUB_CTRL_PHY_CLK |
  		VHUB_CTRL_PHY_RESET_DIS;
  
         /*
  	* We do *NOT* set the VHUB_CTRL_CLK_STOP_SUSPEND bit
  	* to stop the logic clock during suspend because
  	* it causes the registers to become inaccessible and
  	* we haven't yet figured out a good wayt to bring the
  	* controller back into life to issue a wakeup.
  	*/
  
  	/*
  	 * Set some ISO & split control bits according to Aspeed
  	 * recommendation
  	 *
  	 * VHUB_CTRL_ISO_RSP_CTRL: When set tells the HW to respond
  	 * with 0 bytes data packet to ISO IN endpoints when no data
  	 * is available.
  	 *
  	 * VHUB_CTRL_SPLIT_IN: This makes a SOF complete a split IN
  	 * transaction.
  	 */
  	ctrl |= VHUB_CTRL_ISO_RSP_CTRL | VHUB_CTRL_SPLIT_IN;
  	writel(ctrl, vhub->regs + AST_VHUB_CTRL);
  	udelay(1);
  
  	/* Set descriptor ring size */
  	if (AST_VHUB_DESCS_COUNT == 256) {
  		ctrl |= VHUB_CTRL_LONG_DESC;
  		writel(ctrl, vhub->regs + AST_VHUB_CTRL);
  	} else {
  		BUILD_BUG_ON(AST_VHUB_DESCS_COUNT != 32);
  	}
  
  	/* Reset all devices */
  	port_mask = GENMASK(vhub->max_ports, 1);
  	writel(VHUB_SW_RESET_ROOT_HUB |
  	       VHUB_SW_RESET_DMA_CONTROLLER |
  	       VHUB_SW_RESET_EP_POOL |
  	       port_mask, vhub->regs + AST_VHUB_SW_RESET);
  	udelay(1);
  	writel(0, vhub->regs + AST_VHUB_SW_RESET);
  
  	/* Disable and cleanup EP ACK/NACK interrupts */
  	epn_mask = GENMASK(vhub->max_epns - 1, 0);
  	writel(0, vhub->regs + AST_VHUB_EP_ACK_IER);
  	writel(0, vhub->regs + AST_VHUB_EP_NACK_IER);
  	writel(epn_mask, vhub->regs + AST_VHUB_EP_ACK_ISR);
  	writel(epn_mask, vhub->regs + AST_VHUB_EP_NACK_ISR);
  
  	/* Default settings for EP0, enable HW hub EP1 */
  	writel(0, vhub->regs + AST_VHUB_EP0_CTRL);
  	writel(VHUB_EP1_CTRL_RESET_TOGGLE |
  	       VHUB_EP1_CTRL_ENABLE,
  	       vhub->regs + AST_VHUB_EP1_CTRL);
  	writel(0, vhub->regs + AST_VHUB_EP1_STS_CHG);
  
  	/* Configure EP0 DMA buffer */
  	writel(vhub->ep0.buf_dma, vhub->regs + AST_VHUB_EP0_DATA);
  
  	/* Clear address */
  	writel(0, vhub->regs + AST_VHUB_CONF);
  
  	/* Pullup hub (activate on host) */
  	if (vhub->force_usb1)
  		ctrl |= VHUB_CTRL_FULL_SPEED_ONLY;
  
  	ctrl |= VHUB_CTRL_UPSTREAM_CONNECT;
  	writel(ctrl, vhub->regs + AST_VHUB_CTRL);
  
  	/* Enable some interrupts */
  	writel(VHUB_IRQ_HUB_EP0_IN_ACK_STALL |
  	       VHUB_IRQ_HUB_EP0_OUT_ACK_STALL |
  	       VHUB_IRQ_HUB_EP0_SETUP |
  	       VHUB_IRQ_EP_POOL_ACK_STALL |
  	       VHUB_IRQ_BUS_RESUME |
  	       VHUB_IRQ_BUS_SUSPEND |
  	       VHUB_IRQ_BUS_RESET,
  	       vhub->regs + AST_VHUB_IER);
  }
  
  static int ast_vhub_remove(struct platform_device *pdev)
  {
  	struct ast_vhub *vhub = platform_get_drvdata(pdev);
  	unsigned long flags;
  	int i;
  
  	if (!vhub || !vhub->regs)
  		return 0;
  
  	/* Remove devices */
  	for (i = 0; i < vhub->max_ports; i++)
  		ast_vhub_del_dev(&vhub->ports[i].dev);
  
  	spin_lock_irqsave(&vhub->lock, flags);
  
  	/* Mask & ack all interrupts  */
  	writel(0, vhub->regs + AST_VHUB_IER);
  	writel(VHUB_IRQ_ACK_ALL, vhub->regs + AST_VHUB_ISR);
  
  	/* Pull device, leave PHY enabled */
  	writel(VHUB_CTRL_PHY_CLK |
  	       VHUB_CTRL_PHY_RESET_DIS,
  	       vhub->regs + AST_VHUB_CTRL);
  
  	if (vhub->clk)
  		clk_disable_unprepare(vhub->clk);
  
  	spin_unlock_irqrestore(&vhub->lock, flags);
  
  	if (vhub->ep0_bufs)
  		dma_free_coherent(&pdev->dev,
  				  AST_VHUB_EP0_MAX_PACKET *
  				  (vhub->max_ports + 1),
  				  vhub->ep0_bufs,
  				  vhub->ep0_bufs_dma);
  	vhub->ep0_bufs = NULL;
  
  	return 0;
  }
  
  static int ast_vhub_probe(struct platform_device *pdev)
  {
  	enum usb_device_speed max_speed;
  	struct ast_vhub *vhub;
  	struct resource *res;
  	int i, rc = 0;
  	const struct device_node *np = pdev->dev.of_node;
  
  	vhub = devm_kzalloc(&pdev->dev, sizeof(*vhub), GFP_KERNEL);
  	if (!vhub)
  		return -ENOMEM;
  
  	rc = of_property_read_u32(np, "aspeed,vhub-downstream-ports",
  				  &vhub->max_ports);
  	if (rc < 0)
  		vhub->max_ports = AST_VHUB_NUM_PORTS;
  
  	vhub->ports = devm_kcalloc(&pdev->dev, vhub->max_ports,
  				   sizeof(*vhub->ports), GFP_KERNEL);
  	if (!vhub->ports)
  		return -ENOMEM;
  
  	rc = of_property_read_u32(np, "aspeed,vhub-generic-endpoints",
  				  &vhub->max_epns);
  	if (rc < 0)
  		vhub->max_epns = AST_VHUB_NUM_GEN_EPs;
  
  	vhub->epns = devm_kcalloc(&pdev->dev, vhub->max_epns,
  				  sizeof(*vhub->epns), GFP_KERNEL);
  	if (!vhub->epns)
  		return -ENOMEM;
  
  	spin_lock_init(&vhub->lock);
  	vhub->pdev = pdev;
  	vhub->port_irq_mask = GENMASK(VHUB_IRQ_DEV1_BIT + vhub->max_ports - 1,
  				      VHUB_IRQ_DEV1_BIT);
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	vhub->regs = devm_ioremap_resource(&pdev->dev, res);
  	if (IS_ERR(vhub->regs)) {
  		dev_err(&pdev->dev, "Failed to map resources\n");
  		return PTR_ERR(vhub->regs);
  	}
  	UDCDBG(vhub, "vHub@%pR mapped @%p\n", res, vhub->regs);
  
  	platform_set_drvdata(pdev, vhub);
  
  	vhub->clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(vhub->clk)) {
  		rc = PTR_ERR(vhub->clk);
  		goto err;
  	}
  	rc = clk_prepare_enable(vhub->clk);
  	if (rc) {
  		dev_err(&pdev->dev, "Error couldn't enable clock (%d)\n", rc);
  		goto err;
  	}
  
  	/* Check if we need to limit the HW to USB1 */
  	max_speed = usb_get_maximum_speed(&pdev->dev);
  	if (max_speed != USB_SPEED_UNKNOWN && max_speed < USB_SPEED_HIGH)
  		vhub->force_usb1 = true;
  
  	/* Mask & ack all interrupts before installing the handler */
  	writel(0, vhub->regs + AST_VHUB_IER);
  	writel(VHUB_IRQ_ACK_ALL, vhub->regs + AST_VHUB_ISR);
  
  	/* Find interrupt and install handler */
  	vhub->irq = platform_get_irq(pdev, 0);
  	if (vhub->irq < 0) {
  		rc = vhub->irq;
  		goto err;
  	}
  	rc = devm_request_irq(&pdev->dev, vhub->irq, ast_vhub_irq, 0,
  			      KBUILD_MODNAME, vhub);
  	if (rc) {
  		dev_err(&pdev->dev, "Failed to request interrupt\n");
  		goto err;
  	}
  
  	/*
  	 * Allocate DMA buffers for all EP0s in one chunk,
  	 * one per port and one for the vHub itself
  	 */
  	vhub->ep0_bufs = dma_alloc_coherent(&pdev->dev,
  					    AST_VHUB_EP0_MAX_PACKET *
  					    (vhub->max_ports + 1),
  					    &vhub->ep0_bufs_dma, GFP_KERNEL);
  	if (!vhub->ep0_bufs) {
  		dev_err(&pdev->dev, "Failed to allocate EP0 DMA buffers\n");
  		rc = -ENOMEM;
  		goto err;
  	}
  	UDCVDBG(vhub, "EP0 DMA buffers @%p (DMA 0x%08x)\n",
  		vhub->ep0_bufs, (u32)vhub->ep0_bufs_dma);
  
  	/* Init vHub EP0 */
  	ast_vhub_init_ep0(vhub, &vhub->ep0, NULL);
  
  	/* Init devices */
  	for (i = 0; i < vhub->max_ports && rc == 0; i++)
  		rc = ast_vhub_init_dev(vhub, i);
  	if (rc)
  		goto err;
  
  	/* Init hub emulation */
  	rc = ast_vhub_init_hub(vhub);
  	if (rc)
  		goto err;
  
  	/* Initialize HW */
  	ast_vhub_init_hw(vhub);
  
  	dev_info(&pdev->dev, "Initialized virtual hub in USB%d mode\n",
  		 vhub->force_usb1 ? 1 : 2);
  
  	return 0;
   err:
  	ast_vhub_remove(pdev);
  	return rc;
  }
  
  static const struct of_device_id ast_vhub_dt_ids[] = {
  	{
  		.compatible = "aspeed,ast2400-usb-vhub",
  	},
  	{
  		.compatible = "aspeed,ast2500-usb-vhub",
  	},
  	{
  		.compatible = "aspeed,ast2600-usb-vhub",
  	},
  	{ }
  };
  MODULE_DEVICE_TABLE(of, ast_vhub_dt_ids);
  
  static struct platform_driver ast_vhub_driver = {
  	.probe		= ast_vhub_probe,
  	.remove		= ast_vhub_remove,
  	.driver		= {
  		.name	= KBUILD_MODNAME,
  		.of_match_table	= ast_vhub_dt_ids,
  	},
  };
  module_platform_driver(ast_vhub_driver);
  
  MODULE_DESCRIPTION("Aspeed vHub udc driver");
  MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
  MODULE_LICENSE("GPL");
  