[PATCH 2/2] media: rc: add driver for IR remote receiver on MT7623 SoC
Sean Wang
sean.wang at mediatek.com
Thu Jan 5 23:31:25 PST 2017
Hi Sean,
Thanks for your effort for code reviewing. I add comments inline.
On Thu, 2017-01-05 at 17:12 +0000, Sean Young wrote:
> Hi Sean,
>
> Some review comments.
>
> On Fri, Jan 06, 2017 at 12:06:24AM +0800, sean.wang at mediatek.com wrote:
> > From: Sean Wang <sean.wang at mediatek.com>
> >
> > This patch adds driver for IR controller on
> > Mediatek MT7623 SoC. Currently testing successfully
> > on NEC and SONY remote controller only but it should
> > work on others (lirc, rc-5 and rc-6).
> >
> > Signed-off-by: Sean Wang <sean.wang at mediatek.com>
> > ---
> > drivers/media/rc/Kconfig | 10 ++
> > drivers/media/rc/Makefile | 1 +
> > drivers/media/rc/mtk-cir.c | 319 +++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 330 insertions(+)
> > create mode 100644 linux-4.8.rc1_p0/drivers/media/rc/mtk-cir.c
> >
> > diff --git a/drivers/media/rc/Kconfig b/drivers/media/rc/Kconfig
> > index 370e16e..626c500 100644
> > --- a/drivers/media/rc/Kconfig
> > +++ b/drivers/media/rc/Kconfig
> > @@ -389,4 +389,14 @@ config IR_SUNXI
> > To compile this driver as a module, choose M here: the module will
> > be called sunxi-ir.
> >
> > +config IR_MTK
> > + tristate "Mediatek IR remote control"
> > + depends on RC_CORE
> > + depends on ARCH_MEDIATEK || COMPILE_TEST
> > + ---help---
> > + Say Y if you want to use Mediatek internal IR Controller
> > +
> > + To compile this driver as a module, choose M here: the module will
> > + be called mtk-cir.
> > +
> > endif #RC_DEVICES
> > diff --git a/drivers/media/rc/Makefile b/drivers/media/rc/Makefile
> > index 379a5c0..505908d 100644
> > --- a/drivers/media/rc/Makefile
> > +++ b/drivers/media/rc/Makefile
> > @@ -37,3 +37,4 @@ obj-$(CONFIG_IR_TTUSBIR) += ttusbir.o
> > obj-$(CONFIG_RC_ST) += st_rc.o
> > obj-$(CONFIG_IR_SUNXI) += sunxi-cir.o
> > obj-$(CONFIG_IR_IMG) += img-ir/
> > +obj-$(CONFIG_IR_MTK) += mtk-cir.o
> > diff --git a/drivers/media/rc/mtk-cir.c b/drivers/media/rc/mtk-cir.c
> > new file mode 100644
> > index 0000000..4fa4cab
> > --- /dev/null
> > +++ b/drivers/media/rc/mtk-cir.c
> > @@ -0,0 +1,319 @@
> > +/*
> > + * Driver for Mediatek MT7623 IR Receiver Controller
> > + *
> > + * Copyright (C) 2017 Sean Wang <sean.wang at mediatek.com>
> > + *
> > + * 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.
> > + *
> > + * 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/clk.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/module.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/reset.h>
> > +#include <media/rc-core.h>
> > +
> > +#define MTK_IR_DEV "mtk-ir"
>
> KBUILD_MODNAME could be used instead. Currently the module is called
> mtk-cir but the rc device will have driver name mtk-ir.
okay. i will use this instead of this insistent coding.
> > +
> > +/* Register to enable PWM and IR */
> > +#define MTK_CONFIG_HIGH_REG 0x0c
> > +/* Enable IR pulse width detection */
> > +#define MTK_PWM_EN BIT(13)
> > +/* Enable IR hardware function */
> > +#define MTK_IR_EN BIT(0)
> > +
> > +/* Register to setting sample period */
> > +#define MTK_CONFIG_LOW_REG 0x10
> > +/* Field to set sample period */
> > +#define CHK_PERIOD 0xC00
> > +#define MTK_CHK_PERIOD (((CHK_PERIOD) << 8) & (GENMASK(20, 8)))
> > +#define MTK_CHK_PERIOD_MASK (GENMASK(20, 8))
> > +
> > +/* Register to clear state of state machine */
> > +#define MTK_IRCLR_REG 0x20
> > +/* Bit to restart IR receiving */
> > +#define MTK_IRCLR BIT(0)
> > +
> > +/* Register containing pulse width data */
> > +#define MTK_CHKDATA_REG(i) (0x88 + 4 * i)
> > +
> > +/* Register to enable IR interrupt */
> > +#define MTK_IRINT_EN_REG 0xcc
> > +/* Bit to enable interrupt */
> > +#define MTK_IRINT_EN BIT(0)
> > +
> > +/* Register to ack IR interrupt */
> > +#define MTK_IRINT_CLR_REG 0xd0
> > +/* Bit to clear interrupt status */
> > +#define MTK_IRINT_CLR BIT(0)
> > +
> > +/* Number of registers to record the pulse width */
> > +#define MTK_CHKDATA_SZ 17
> > +/* Required frequency */
> > +#define MTK_IR_BASE_CLK 273000000
> > +/* Frequency after IR internal divider */
> > +#define MTK_IR_CLK (MTK_IR_BASE_CLK / 4)
> > +/* Sample period in ns */
> > +#define MTK_IR_SAMPLE (((1000000000ul / MTK_IR_CLK) * CHK_PERIOD))
> > +/* Indicate the end of IR data*/
> > +#define MTK_IR_END(v) (v == 0xff)
> > +
> > +/* struct mtk_ir - This is the main datasructure for holding the state
> > + * of the driver
> > + * @dev: The device pointer
> > + * @ir_lock: Make sure that synchronization between remove and ISR
> > + * @rc: The rc instrance
> > + * @base: The mapped register i/o base
> > + * @irq: The IRQ that we are using
> > + * @clk: The clock that we are using
> > + * @map_name: The name for keymap lookup
> > + */
> > +struct mtk_ir {
> > + struct device *dev;
> > + /*Protect concurrency between driver removal and ISR*/
> > + spinlock_t ir_lock;
> > + struct rc_dev *rc;
> > + void __iomem *base;
> > + int irq;
> > + struct clk *clk;
> > + const char *map_name;
>
> irq and map_name don't need to be stored here, they're only used in
> mtk_ir_probe.
>
I will remove map_name , but keep irq for synchronize_irq call needs.
> > +};
> > +
> > +static void mtk_w32_mask(struct mtk_ir *ir, u32 val, u32 mask, unsigned int reg)
> > +{
> > + u32 tmp;
> > +
> > + tmp = __raw_readl(ir->base + reg);
> > + tmp = (tmp & ~mask) | val;
> > + __raw_writel(tmp, ir->base + reg);
> > +}
> > +
> > +static void mtk_w32(struct mtk_ir *ir, u32 val, unsigned int reg)
> > +{
> > + __raw_writel(val, ir->base + reg);
> > +}
> > +
> > +static u32 mtk_r32(struct mtk_ir *ir, unsigned int reg)
> > +{
> > + return __raw_readl(ir->base + reg);
> > +}
> > +
> > +static inline void mtk_irq_disable(struct mtk_ir *ir, u32 mask)
> > +{
> > + u32 val;
> > +
> > + val = mtk_r32(ir, MTK_IRINT_EN_REG);
> > + mtk_w32(ir, val & ~mask, MTK_IRINT_EN_REG);
> > +}
> > +
> > +static inline void mtk_irq_enable(struct mtk_ir *ir, u32 mask)
> > +{
> > + u32 val;
> > +
> > + val = mtk_r32(ir, MTK_IRINT_EN_REG);
> > + mtk_w32(ir, val | mask, MTK_IRINT_EN_REG);
> > +}
> > +
> > +static irqreturn_t mtk_ir_irq(int irqno, void *dev_id)
> > +{
> > + struct mtk_ir *ir = dev_id;
> > + u8 wid = 0;
> > + u32 i, j, val;
> > + DEFINE_IR_RAW_EVENT(rawir);
> > +
> > + spin_lock(&ir->ir_lock);
> > +
> > + mtk_irq_disable(ir, MTK_IRINT_EN);
> > +
> > + /* Reset decoder state machine */
> > + ir_raw_event_reset(ir->rc);
> > +
> > + /* First message must be pulse */
> > + rawir.pulse = false;
> > +
> > + /* Handle pulse and space until end of message */
> > + for (i = 0 ; i < MTK_CHKDATA_SZ ; i++) {
> > + val = mtk_r32(ir, MTK_CHKDATA_REG(i));
> > + dev_dbg(ir->dev, "@reg%d=0x%08x\n", i, val);
> > +
> > + for (j = 0 ; j < 4 ; j++) {
> > + wid = (val & (0xff << j * 8)) >> j * 8;
> > + rawir.pulse = !rawir.pulse;
> > + rawir.duration = wid * (MTK_IR_SAMPLE + 1);
> > + ir_raw_event_store_with_filter(ir->rc, &rawir);
> > +
> > + if (MTK_IR_END(wid))
> > + goto end_msg;
> > + }
> > + }
>
> If I read this correctly, there is a maximum of 17 * 4 = 68 edges per
> IR message. The rc6 mce key 0 (scancode 0x800f0400) is 69 edges, so that
> won't work.
>
Uh, this is related to hardware limitation. Maximum number hardware
holds indeed is only 68 edges as you said :(
For the case, I will try change the logic into that the whole message
is dropped if no end of message is seen within 68 counts to avoid
wasting CPU for decoding.
> > +end_msg:
> > + /* Restart the next receive */
> > + mtk_w32_mask(ir, 0x1, MTK_IRCLR, MTK_IRCLR_REG);
> > +
> > + ir_raw_event_set_idle(ir->rc, true);
> > + ir_raw_event_handle(ir->rc);
> > +
> > + /* Clear interrupt status */
> > + mtk_w32_mask(ir, 0x1, MTK_IRINT_CLR, MTK_IRINT_CLR_REG);
> > +
> > + /* Enable interrupt */
> > + mtk_irq_enable(ir, MTK_IRINT_EN);
> > +
> > + spin_unlock(&ir->ir_lock);
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static int mtk_ir_probe(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct device_node *dn = dev->of_node;
> > + struct resource *res;
> > + struct mtk_ir *ir;
> > + u32 val;
> > + int ret = 0;
> > +
> > + ir = devm_kzalloc(dev, sizeof(struct mtk_ir), GFP_KERNEL);
> > + if (!ir)
> > + return -ENOMEM;
> > +
> > + spin_lock_init(&ir->ir_lock);
> > +
> > + ir->dev = dev;
> > +
> > + if (!of_device_is_compatible(dn, "mediatek,mt7623-ir"))
> > + return -ENODEV;
> > +
> > + ir->clk = devm_clk_get(dev, "clk");
> > + if (IS_ERR(ir->clk)) {
> > + dev_err(dev, "failed to get a ir clock.\n");
> > + return PTR_ERR(ir->clk);
> > + }
> > +
> > + if (clk_prepare_enable(ir->clk)) {
> > + dev_err(dev, "try to enable ir_clk failed\n");
> > + ret = -EINVAL;
> > + goto exit_clkdisable_clk;
> > + }
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + ir->base = devm_ioremap_resource(dev, res);
> > + if (IS_ERR(ir->base)) {
> > + dev_err(dev, "failed to map registers\n");
> > + ret = PTR_ERR(ir->base);
> > + goto exit_clkdisable_clk;
> > + }
> > +
> > + ir->rc = rc_allocate_device();
> > + if (!ir->rc) {
> > + dev_err(dev, "failed to allocate device\n");
> > + ret = -ENOMEM;
> > + goto exit_clkdisable_clk;
> > + }
> > +
> > + ir->rc->priv = ir;
> > + ir->rc->input_name = MTK_IR_DEV;
> > + ir->rc->input_phys = "mtk-ir/input0";
> > + ir->rc->input_id.bustype = BUS_HOST;
> > + ir->rc->input_id.vendor = 0x0001;
> > + ir->rc->input_id.product = 0x0001;
> > + ir->rc->input_id.version = 0x0001;
> > + ir->map_name = of_get_property(dn, "linux,rc-map-name", NULL);
> > + ir->rc->map_name = ir->map_name ?: RC_MAP_EMPTY;
> > + ir->rc->dev.parent = dev;
> > + ir->rc->driver_type = RC_DRIVER_IR_RAW;
> > + ir->rc->driver_name = MTK_IR_DEV;
> > + ir->rc->allowed_protocols = RC_BIT_ALL;
> > + ir->rc->rx_resolution = MTK_IR_SAMPLE;
> > +
> > + ret = rc_register_device(ir->rc);
> > + if (ret) {
> > + dev_err(dev, "failed to register rc device\n");
> > + goto exit_free_dev;
> > + }
> > +
> > + platform_set_drvdata(pdev, ir);
> > +
> > + ir->irq = platform_get_irq(pdev, 0);
> > + if (ir->irq < 0) {
> > + dev_err(dev, "no irq resource\n");
> > + ret = ir->irq;
>
> From here on onwards the errors paths should call rc_unregister_device(),
> and no longer call rc_free_device(). Note that current master has
> devm_rc_allocate_device() and devm_rc_register_device() which would
> simplify this code.
okay, i will use devm_rc_register_device to have simplified code.
> > + goto exit_free_dev;
> > + }
> > +
> > + ret = devm_request_irq(dev, ir->irq, mtk_ir_irq, 0, MTK_IR_DEV, ir);
> > + if (ret) {
> > + dev_err(dev, "failed request irq\n");
> > + goto exit_free_dev;
> > + }
> > +
> > + mtk_irq_disable(ir, MTK_IRINT_EN);
> > +
> > + val = mtk_r32(ir, MTK_CONFIG_HIGH_REG);
> > + val |= MTK_PWM_EN | MTK_IR_EN;
> > + mtk_w32(ir, val, MTK_CONFIG_HIGH_REG);
> > +
> > + /* Setting sample period */
> > + mtk_w32_mask(ir, MTK_CHK_PERIOD, MTK_CHK_PERIOD_MASK,
> > + MTK_CONFIG_LOW_REG);
> > +
> > + mtk_irq_enable(ir, MTK_IRINT_EN);
> > +
> > + dev_info(dev, "initialized MT7623 IR driver\n");
> > + return 0;
> > +
> > +exit_free_dev:
> > + rc_free_device(ir->rc);
> > +exit_clkdisable_clk:
> > + clk_disable_unprepare(ir->clk);
> > +
> > + return ret;
> > +}
> > +
> > +static int mtk_ir_remove(struct platform_device *pdev)
> > +{
> > + unsigned long flags;
> > +
> > + struct mtk_ir *ir = platform_get_drvdata(pdev);
> > +
> > + spin_lock_irqsave(&ir->ir_lock, flags);
> > +
> > + mtk_irq_disable(ir, MTK_IRINT_EN);
> > +
> > + clk_disable_unprepare(ir->clk);
> > +
> > + spin_unlock_irqrestore(&ir->ir_lock, flags);
>
> I'm not convinced the ir_lock is helping to prevent any race condition. An
> irq might still already have occurred which will now try to use ir->rc
> which is freed. You can remove the spinlock completely and call
> sychronize_irq() after disabling the mtk interrupt. That way you're sure
> the remove is safe to complete.
Okay, it's great suggestion. I will use sychronize_irq instead of the my
bad one :)
> > +
> > + rc_unregister_device(ir->rc);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct of_device_id mtk_ir_match[] = {
> > + { .compatible = "mediatek,mt7623-ir" },
> > + {},
> > +};
> > +MODULE_DEVICE_TABLE(of, mtk_ir_match);
> > +
> > +static struct platform_driver mtk_ir_driver = {
> > + .probe = mtk_ir_probe,
> > + .remove = mtk_ir_remove,
> > + .driver = {
> > + .name = MTK_IR_DEV,
> > + .of_match_table = mtk_ir_match,
> > + },
> > +};
> > +
> > +module_platform_driver(mtk_ir_driver);
> > +
> > +MODULE_DESCRIPTION("Mediatek MT7623 IR Receiver Controller Driver");
> > +MODULE_AUTHOR("Sean Wang <sean.wang at mediatek.com>");
> > +MODULE_LICENSE("GPL");
> > --
> > 1.9.1
> >
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