// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * APM X-Gene SLIMpro MailBox Driver
   *
   * Copyright (c) 2015, Applied Micro Circuits Corporation
   * Author: Feng Kan fkan@apm.com

   */
  #include <linux/acpi.h>
  #include <linux/delay.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/mailbox_controller.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/spinlock.h>
  
  #define MBOX_CON_NAME			"slimpro-mbox"
  #define MBOX_REG_SET_OFFSET		0x1000
  #define MBOX_CNT			8
  #define MBOX_STATUS_AVAIL_MASK		BIT(16)
  #define MBOX_STATUS_ACK_MASK		BIT(0)
  
  /* Configuration and Status Registers */
  #define REG_DB_IN		0x00
  #define REG_DB_DIN0		0x04
  #define REG_DB_DIN1		0x08
  #define REG_DB_OUT		0x10
  #define REG_DB_DOUT0		0x14
  #define REG_DB_DOUT1		0x18
  #define REG_DB_STAT		0x20
  #define REG_DB_STATMASK		0x24
  
  /**
   * X-Gene SlimPRO mailbox channel information
   *
   * @dev:	Device to which it is attached
   * @chan:	Pointer to mailbox communication channel
   * @reg:	Base address to access channel registers
   * @irq:	Interrupt number of the channel
   * @rx_msg:	Received message storage
   */
  struct slimpro_mbox_chan {
  	struct device		*dev;
  	struct mbox_chan	*chan;
  	void __iomem		*reg;
  	int			irq;
  	u32			rx_msg[3];
  };
  
  /**
   * X-Gene SlimPRO Mailbox controller data
   *
   * X-Gene SlimPRO Mailbox controller has 8 commnunication channels.
   * Each channel has a separate IRQ number assgined to it.
   *
   * @mb_ctrl:	Representation of the commnunication channel controller
   * @mc:		Array of SlimPRO mailbox channels of the controller
   * @chans:	Array of mailbox communication channels
   *
   */
  struct slimpro_mbox {
  	struct mbox_controller		mb_ctrl;
  	struct slimpro_mbox_chan	mc[MBOX_CNT];
  	struct mbox_chan		chans[MBOX_CNT];
  };
  
  static void mb_chan_send_msg(struct slimpro_mbox_chan *mb_chan, u32 *msg)
  {
  	writel(msg[1], mb_chan->reg + REG_DB_DOUT0);
  	writel(msg[2], mb_chan->reg + REG_DB_DOUT1);
  	writel(msg[0], mb_chan->reg + REG_DB_OUT);
  }
  
  static void mb_chan_recv_msg(struct slimpro_mbox_chan *mb_chan)
  {
  	mb_chan->rx_msg[1] = readl(mb_chan->reg + REG_DB_DIN0);
  	mb_chan->rx_msg[2] = readl(mb_chan->reg + REG_DB_DIN1);
  	mb_chan->rx_msg[0] = readl(mb_chan->reg + REG_DB_IN);
  }
  
  static int mb_chan_status_ack(struct slimpro_mbox_chan *mb_chan)
  {
  	u32 val = readl(mb_chan->reg + REG_DB_STAT);
  
  	if (val & MBOX_STATUS_ACK_MASK) {
  		writel(MBOX_STATUS_ACK_MASK, mb_chan->reg + REG_DB_STAT);
  		return 1;
  	}
  	return 0;
  }
  
  static int mb_chan_status_avail(struct slimpro_mbox_chan *mb_chan)
  {
  	u32 val = readl(mb_chan->reg + REG_DB_STAT);
  
  	if (val & MBOX_STATUS_AVAIL_MASK) {
  		mb_chan_recv_msg(mb_chan);
  		writel(MBOX_STATUS_AVAIL_MASK, mb_chan->reg + REG_DB_STAT);
  		return 1;
  	}
  	return 0;
  }
  
  static irqreturn_t slimpro_mbox_irq(int irq, void *id)
  {
  	struct slimpro_mbox_chan *mb_chan = id;
  
  	if (mb_chan_status_ack(mb_chan))
  		mbox_chan_txdone(mb_chan->chan, 0);
  
  	if (mb_chan_status_avail(mb_chan))
  		mbox_chan_received_data(mb_chan->chan, mb_chan->rx_msg);
  
  	return IRQ_HANDLED;
  }
  
  static int slimpro_mbox_send_data(struct mbox_chan *chan, void *msg)
  {
  	struct slimpro_mbox_chan *mb_chan = chan->con_priv;
  
  	mb_chan_send_msg(mb_chan, msg);
  	return 0;
  }
  
  static int slimpro_mbox_startup(struct mbox_chan *chan)
  {
  	struct slimpro_mbox_chan *mb_chan = chan->con_priv;
  	int rc;
  	u32 val;
  
  	rc = devm_request_irq(mb_chan->dev, mb_chan->irq, slimpro_mbox_irq, 0,
  			      MBOX_CON_NAME, mb_chan);
  	if (unlikely(rc)) {
  		dev_err(mb_chan->dev, "failed to register mailbox interrupt %d
  ",
  			mb_chan->irq);
  		return rc;
  	}
  
  	/* Enable HW interrupt */
  	writel(MBOX_STATUS_ACK_MASK | MBOX_STATUS_AVAIL_MASK,
  	       mb_chan->reg + REG_DB_STAT);
  	/* Unmask doorbell status interrupt */
  	val = readl(mb_chan->reg + REG_DB_STATMASK);
  	val &= ~(MBOX_STATUS_ACK_MASK | MBOX_STATUS_AVAIL_MASK);
  	writel(val, mb_chan->reg + REG_DB_STATMASK);
  
  	return 0;
  }
  
  static void slimpro_mbox_shutdown(struct mbox_chan *chan)
  {
  	struct slimpro_mbox_chan *mb_chan = chan->con_priv;
  	u32 val;
  
  	/* Mask doorbell status interrupt */
  	val = readl(mb_chan->reg + REG_DB_STATMASK);
  	val |= (MBOX_STATUS_ACK_MASK | MBOX_STATUS_AVAIL_MASK);
  	writel(val, mb_chan->reg + REG_DB_STATMASK);
  
  	devm_free_irq(mb_chan->dev, mb_chan->irq, mb_chan);
  }

  static const struct mbox_chan_ops slimpro_mbox_ops = {

  	.send_data = slimpro_mbox_send_data,
  	.startup = slimpro_mbox_startup,
  	.shutdown = slimpro_mbox_shutdown,
  };
  
  static int slimpro_mbox_probe(struct platform_device *pdev)
  {
  	struct slimpro_mbox *ctx;
  	struct resource *regs;
  	void __iomem *mb_base;
  	int rc;
  	int i;
  
  	ctx = devm_kzalloc(&pdev->dev, sizeof(struct slimpro_mbox), GFP_KERNEL);

  	if (!ctx)
  		return -ENOMEM;

  
  	platform_set_drvdata(pdev, ctx);
  
  	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);

  	mb_base = devm_ioremap_resource(&pdev->dev, regs);
  	if (IS_ERR(mb_base))
  		return PTR_ERR(mb_base);

  
  	/* Setup mailbox links */
  	for (i = 0; i < MBOX_CNT; i++) {
  		ctx->mc[i].irq = platform_get_irq(pdev, i);
  		if (ctx->mc[i].irq < 0) {
  			if (i == 0) {
  				dev_err(&pdev->dev, "no available IRQ
  ");
  				return -EINVAL;
  			}
  			dev_info(&pdev->dev, "no IRQ for channel %d
  ", i);
  			break;
  		}
  
  		ctx->mc[i].dev = &pdev->dev;
  		ctx->mc[i].reg = mb_base + i * MBOX_REG_SET_OFFSET;
  		ctx->mc[i].chan = &ctx->chans[i];
  		ctx->chans[i].con_priv = &ctx->mc[i];
  	}
  
  	/* Setup mailbox controller */
  	ctx->mb_ctrl.dev = &pdev->dev;
  	ctx->mb_ctrl.chans = ctx->chans;
  	ctx->mb_ctrl.txdone_irq = true;
  	ctx->mb_ctrl.ops = &slimpro_mbox_ops;
  	ctx->mb_ctrl.num_chans = i;

  	rc = devm_mbox_controller_register(&pdev->dev, &ctx->mb_ctrl);

  	if (rc) {
  		dev_err(&pdev->dev,
  			"APM X-Gene SLIMpro MailBox register failed:%d
  ", rc);
  		return rc;
  	}
  
  	dev_info(&pdev->dev, "APM X-Gene SLIMpro MailBox registered
  ");
  	return 0;
  }

  static const struct of_device_id slimpro_of_match[] = {
  	{.compatible = "apm,xgene-slimpro-mbox" },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, slimpro_of_match);
  
  #ifdef CONFIG_ACPI
  static const struct acpi_device_id slimpro_acpi_ids[] = {
  	{"APMC0D01", 0},
  	{}
  };
  MODULE_DEVICE_TABLE(acpi, slimpro_acpi_ids);
  #endif
  
  static struct platform_driver slimpro_mbox_driver = {
  	.probe	= slimpro_mbox_probe,

  	.driver	= {
  		.name = "xgene-slimpro-mbox",
  		.of_match_table = of_match_ptr(slimpro_of_match),
  		.acpi_match_table = ACPI_PTR(slimpro_acpi_ids)
  	},
  };
  
  static int __init slimpro_mbox_init(void)
  {
  	return platform_driver_register(&slimpro_mbox_driver);
  }
  
  static void __exit slimpro_mbox_exit(void)
  {
  	platform_driver_unregister(&slimpro_mbox_driver);
  }
  
  subsys_initcall(slimpro_mbox_init);
  module_exit(slimpro_mbox_exit);
  
  MODULE_DESCRIPTION("APM X-Gene SLIMpro Mailbox Driver");
  MODULE_LICENSE("GPL");