/*
   * Driver for Amlogic Meson IR remote receiver
   *
   * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * version 2 as published by the Free Software Foundation.
   *
   * 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/device.h>
  #include <linux/err.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/module.h>
  #include <linux/of_platform.h>
  #include <linux/platform_device.h>
  #include <linux/spinlock.h>
  
  #include <media/rc-core.h>
  
  #define DRIVER_NAME		"meson-ir"
  
  #define IR_DEC_LDR_ACTIVE	0x00
  #define IR_DEC_LDR_IDLE		0x04
  #define IR_DEC_LDR_REPEAT	0x08
  #define IR_DEC_BIT_0		0x0c
  #define IR_DEC_REG0		0x10
  #define IR_DEC_FRAME		0x14
  #define IR_DEC_STATUS		0x18
  #define IR_DEC_REG1		0x1c
  
  #define REG0_RATE_MASK		(BIT(11) - 1)
  
  #define REG1_MODE_MASK		(BIT(7) | BIT(8))
  #define REG1_MODE_NEC		(0 << 7)
  #define REG1_MODE_GENERAL	(2 << 7)
  
  #define REG1_TIME_IV_SHIFT	16
  #define REG1_TIME_IV_MASK	((BIT(13) - 1) << REG1_TIME_IV_SHIFT)
  
  #define REG1_IRQSEL_MASK	(BIT(2) | BIT(3))
  #define REG1_IRQSEL_NEC_MODE	(0 << 2)
  #define REG1_IRQSEL_RISE_FALL	(1 << 2)
  #define REG1_IRQSEL_FALL	(2 << 2)
  #define REG1_IRQSEL_RISE	(3 << 2)
  
  #define REG1_RESET		BIT(0)
  #define REG1_ENABLE		BIT(15)
  
  #define STATUS_IR_DEC_IN	BIT(8)
  
  #define MESON_TRATE		10	/* us */
  
  struct meson_ir {
  	void __iomem	*reg;
  	struct rc_dev	*rc;
  	int		irq;
  	spinlock_t	lock;
  };
  
  static void meson_ir_set_mask(struct meson_ir *ir, unsigned int reg,
  			      u32 mask, u32 value)
  {
  	u32 data;
  
  	data = readl(ir->reg + reg);
  	data &= ~mask;
  	data |= (value & mask);
  	writel(data, ir->reg + reg);
  }
  
  static irqreturn_t meson_ir_irq(int irqno, void *dev_id)
  {
  	struct meson_ir *ir = dev_id;
  	u32 duration;
  	DEFINE_IR_RAW_EVENT(rawir);
  
  	spin_lock(&ir->lock);
  
  	duration = readl(ir->reg + IR_DEC_REG1);
  	duration = (duration & REG1_TIME_IV_MASK) >> REG1_TIME_IV_SHIFT;
  	rawir.duration = US_TO_NS(duration * MESON_TRATE);
  
  	rawir.pulse = !!(readl(ir->reg + IR_DEC_STATUS) & STATUS_IR_DEC_IN);
  
  	ir_raw_event_store_with_filter(ir->rc, &rawir);
  	ir_raw_event_handle(ir->rc);
  
  	spin_unlock(&ir->lock);
  
  	return IRQ_HANDLED;
  }
  
  static int meson_ir_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct device_node *node = dev->of_node;
  	struct resource *res;
  	const char *map_name;
  	struct meson_ir *ir;
  	int ret;
  
  	ir = devm_kzalloc(dev, sizeof(struct meson_ir), GFP_KERNEL);
  	if (!ir)
  		return -ENOMEM;
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	ir->reg = devm_ioremap_resource(dev, res);
  	if (IS_ERR(ir->reg)) {
  		dev_err(dev, "failed to map registers
  ");
  		return PTR_ERR(ir->reg);
  	}
  
  	ir->irq = platform_get_irq(pdev, 0);
  	if (ir->irq < 0) {
  		dev_err(dev, "no irq resource
  ");
  		return ir->irq;
  	}
  
  	ir->rc = rc_allocate_device();
  	if (!ir->rc) {
  		dev_err(dev, "failed to allocate rc device
  ");
  		return -ENOMEM;
  	}
  
  	ir->rc->priv = ir;
  	ir->rc->input_name = DRIVER_NAME;
  	ir->rc->input_phys = DRIVER_NAME "/input0";
  	ir->rc->input_id.bustype = BUS_HOST;
  	map_name = of_get_property(node, "linux,rc-map-name", NULL);
  	ir->rc->map_name = map_name ? map_name : RC_MAP_EMPTY;
  	ir->rc->dev.parent = dev;
  	ir->rc->driver_type = RC_DRIVER_IR_RAW;
  	ir->rc->allowed_protocols = RC_BIT_ALL;
  	ir->rc->rx_resolution = US_TO_NS(MESON_TRATE);
  	ir->rc->timeout = MS_TO_NS(200);
  	ir->rc->driver_name = DRIVER_NAME;
  
  	spin_lock_init(&ir->lock);
  	platform_set_drvdata(pdev, ir);
  
  	ret = rc_register_device(ir->rc);
  	if (ret) {
  		dev_err(dev, "failed to register rc device
  ");
  		goto out_free;
  	}
  
  	ret = devm_request_irq(dev, ir->irq, meson_ir_irq, 0, "ir-meson", ir);
  	if (ret) {
  		dev_err(dev, "failed to request irq
  ");
  		goto out_unreg;
  	}
  
  	/* Reset the decoder */
  	meson_ir_set_mask(ir, IR_DEC_REG1, REG1_RESET, REG1_RESET);
  	meson_ir_set_mask(ir, IR_DEC_REG1, REG1_RESET, 0);
  	/* Set general operation mode */
  	meson_ir_set_mask(ir, IR_DEC_REG1, REG1_MODE_MASK, REG1_MODE_GENERAL);
  	/* Set rate */
  	meson_ir_set_mask(ir, IR_DEC_REG0, REG0_RATE_MASK, MESON_TRATE - 1);
  	/* IRQ on rising and falling edges */
  	meson_ir_set_mask(ir, IR_DEC_REG1, REG1_IRQSEL_MASK,
  			  REG1_IRQSEL_RISE_FALL);
  	/* Enable the decoder */
  	meson_ir_set_mask(ir, IR_DEC_REG1, REG1_ENABLE, REG1_ENABLE);
  
  	dev_info(dev, "receiver initialized
  ");
  
  	return 0;
  out_unreg:
  	rc_unregister_device(ir->rc);
  	ir->rc = NULL;
  out_free:
  	rc_free_device(ir->rc);
  
  	return ret;
  }
  
  static int meson_ir_remove(struct platform_device *pdev)
  {
  	struct meson_ir *ir = platform_get_drvdata(pdev);
  	unsigned long flags;
  
  	/* Disable the decoder */
  	spin_lock_irqsave(&ir->lock, flags);
  	meson_ir_set_mask(ir, IR_DEC_REG1, REG1_ENABLE, 0);
  	spin_unlock_irqrestore(&ir->lock, flags);
  
  	rc_unregister_device(ir->rc);
  
  	return 0;
  }
  
  static const struct of_device_id meson_ir_match[] = {
  	{ .compatible = "amlogic,meson6-ir" },
  	{ },
  };
  
  static struct platform_driver meson_ir_driver = {
  	.probe		= meson_ir_probe,
  	.remove		= meson_ir_remove,
  	.driver = {
  		.name		= DRIVER_NAME,
  		.of_match_table	= meson_ir_match,
  	},
  };
  
  module_platform_driver(meson_ir_driver);
  
  MODULE_DESCRIPTION("Amlogic Meson IR remote receiver driver");
  MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
  MODULE_LICENSE("GPL v2");