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Date:   Fri, 16 Jul 2021 19:01:33 +0300
From:   Viktor Prutyanov <viktor.prutyanov@phystech.edu>
To:     Sean Young <sean@mess.org>
Cc:     mchehab@kernel.org, robh+dt@kernel.org, khilman@baylibre.com,
        narmstrong@baylibre.com, jbrunet@baylibre.com,
        martin.blumenstingl@googlemail.com, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-amlogic@lists.infradead.org, rockosov@gmail.com
Subject: Re: [PATCH v6 2/2] media: rc: introduce Meson IR TX driver
Message-ID: <20210716190133.261a50b4@192.168.1.3>
In-Reply-To: <20210716153426.GA6907@gofer.mess.org>
References: <20210716144508.6058-1-viktor.prutyanov@phystech.edu>
        <20210716144508.6058-3-viktor.prutyanov@phystech.edu>
        <20210716153426.GA6907@gofer.mess.org>
Organization: MIPT
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Precedence: bulk

Hi Sean,

On Fri, 16 Jul 2021 16:34:26 +0100
Sean Young <sean@mess.org> wrote:

> On Fri, Jul 16, 2021 at 05:45:08PM +0300, Viktor Prutyanov wrote:
> > This patch adds the driver for Amlogic Meson IR transmitter.
> > 
> > Some Amlogic SoCs such as A311D and T950D4 have IR transmitter
> > (also called blaster) controller onboard. It is capable of sending
> > IR signals with arbitrary carrier frequency and duty cycle.
> > 
> > The driver supports 2 modulation clock sources:
> >  - xtal3 clock (xtal divided by 3)
> >  - 1us clock
> > 
> > Signed-off-by: Viktor Prutyanov <viktor.prutyanov@phystech.edu>
> > ---
> >  changes in v2:
> >    - threaded IRQ removed, all stuff done in IRQ handler
> >    - DIV_ROUND_CLOSEST_ULL replaced with DIV_ROUND_CLOSEST
> >    - compatible changed to "amlogic,meson-g12a-irblaster"
> >    - 'debug' parameter removed
> >    - dprintk() replaced with dev_dbg()/dev_info()
> >    - carrier frequency checked against 0
> >    - device_name added
> >  changes in v3:
> >    - license header fixed
> >    - 'max_fifo_level' parameter removed
> >    - irq and clk_nr deleted from irblaster_dev struct
> >    - some divisions replaced with DIV_ROUND_CLOSEST
> >    - irb_send inlined
> >    - fixed early completion in IRQ handler
> >    - spin lock added before kfree
> >  changes in v4:
> >    - irblaster -> ir-tx renaming
> >    - spin lock added before buffer allocation
> >  changes in v5:
> >    - spinlocks rework made in meson_irtx_transmit
> >    - max_fifo_level replaced with fifo_threshold (max_fifo_level +
> >      fifo_threshold == IRB_FIFO_LEN == 128)
> >    - max-fifo-level -> amlogic,fifo-threshold
> >  changes in v6:
> >    - interruptible wait replaced with uninterruptible with timeout
> >    - completion done check added to IRQ handler
> > 
> >  drivers/media/rc/Kconfig       |  10 +
> >  drivers/media/rc/Makefile      |   1 +
> >  drivers/media/rc/meson-ir-tx.c | 415
> > +++++++++++++++++++++++++++++++++ 3 files changed, 426 insertions(+)
> >  create mode 100644 drivers/media/rc/meson-ir-tx.c
> > 
> > diff --git a/drivers/media/rc/Kconfig b/drivers/media/rc/Kconfig
> > index d0a8326b75c2..fd5a7a058714 100644
> > --- a/drivers/media/rc/Kconfig
> > +++ b/drivers/media/rc/Kconfig
> > @@ -246,6 +246,16 @@ config IR_MESON
> >  	   To compile this driver as a module, choose M here: the
> >  	   module will be called meson-ir.
> >  
> > +config IR_MESON_TX
> > +	tristate "Amlogic Meson IR TX"
> > +	depends on ARCH_MESON || COMPILE_TEST
> > +	help
> > +	   Say Y if you want to use the IR transmitter available on
> > +	   Amlogic Meson SoCs.
> > +
> > +	   To compile this driver as a module, choose M here: the
> > +	   module will be called meson-ir-tx.
> > +
> >  config IR_MTK
> >  	tristate "Mediatek IR remote receiver"
> >  	depends on ARCH_MEDIATEK || COMPILE_TEST
> > diff --git a/drivers/media/rc/Makefile b/drivers/media/rc/Makefile
> > index 692e9b6b203f..0db51fad27d6 100644
> > --- a/drivers/media/rc/Makefile
> > +++ b/drivers/media/rc/Makefile
> > @@ -28,6 +28,7 @@ obj-$(CONFIG_IR_ITE_CIR) += ite-cir.o
> >  obj-$(CONFIG_IR_MCEUSB) += mceusb.o
> >  obj-$(CONFIG_IR_FINTEK) += fintek-cir.o
> >  obj-$(CONFIG_IR_MESON) += meson-ir.o
> > +obj-$(CONFIG_IR_MESON_TX) += meson-ir-tx.o
> >  obj-$(CONFIG_IR_NUVOTON) += nuvoton-cir.o
> >  obj-$(CONFIG_IR_ENE) += ene_ir.o
> >  obj-$(CONFIG_IR_REDRAT3) += redrat3.o
> > diff --git a/drivers/media/rc/meson-ir-tx.c
> > b/drivers/media/rc/meson-ir-tx.c new file mode 100644
> > index 000000000000..77e276e3dbe8
> > --- /dev/null
> > +++ b/drivers/media/rc/meson-ir-tx.c
> > @@ -0,0 +1,415 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/**
> > + * meson-ir-tx.c - Amlogic Meson IR TX driver
> > + *
> > + * Copyright (c) 2021, SberDevices. All Rights Reserved.
> > + *
> > + * Author: Viktor Prutyanov <viktor.prutyanov@phystech.edu>
> > + */
> > +
> > +#include <linux/device.h>
> > +#include <linux/module.h>
> > +#include <linux/sched.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/of.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/spinlock.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/clk.h>
> > +#include <linux/slab.h>
> > +#include <media/rc-core.h>
> > +
> > +#define DEVICE_NAME	"Meson IR TX"
> > +#define DRIVER_NAME	"meson-ir-tx"
> > +
> > +#define MIRTX_DEFAULT_CARRIER		38000
> > +#define MIRTX_DEFAULT_DUTY_CYCLE	50
> > +#define MIRTX_DEFAULT_FIFO_THD		32
> > +#define MIRTX_TIMEOUT_US		(IR_MAX_DURATION /
> > NSEC_PER_USEC)  
> 
> IR_MAX_DURATION is already in microseconds, see commit 528222d853f9.
> Now the wait_for_completion_timeout() gets 500us as the timeout. Has
> this been tested?
>
Thanks for noticing this issue. I usually test each patch version on
two versions of the kernel, but now I forgot to check on a new one, I
will fix it.
 
> Looks good otherwise
> 
> Thanks
> Sean
> 
> > +
> > +#define IRB_MOD_1US_CLK_RATE	1000000
> > +
> > +#define IRB_FIFO_LEN	128
> > +
> > +#define IRB_ADDR0	0x0
> > +#define IRB_ADDR1	0x4
> > +#define IRB_ADDR2	0x8
> > +#define IRB_ADDR3	0xc
> > +
> > +#define IRB_MAX_DELAY	(1 << 10)
> > +#define IRB_DELAY_MASK	(IRB_MAX_DELAY - 1)
> > +
> > +/* IRCTRL_IR_BLASTER_ADDR0 */
> > +#define IRB_MOD_CLK(x)		((x) << 12)
> > +#define IRB_MOD_SYS_CLK		0
> > +#define IRB_MOD_XTAL3_CLK	1
> > +#define IRB_MOD_1US_CLK		2
> > +#define IRB_MOD_10US_CLK	3
> > +#define IRB_INIT_HIGH		BIT(2)
> > +#define IRB_ENABLE		BIT(0)
> > +
> > +/* IRCTRL_IR_BLASTER_ADDR2 */
> > +#define IRB_MOD_COUNT(lo, hi)	((((lo) - 1) << 16) | ((hi) -
> > 1)) +
> > +/* IRCTRL_IR_BLASTER_ADDR2 */
> > +#define IRB_WRITE_FIFO	BIT(16)
> > +#define IRB_MOD_ENABLE	BIT(12)
> > +#define IRB_TB_1US	(0x0 << 10)
> > +#define IRB_TB_10US	(0x1 << 10)
> > +#define IRB_TB_100US	(0x2 << 10)
> > +#define IRB_TB_MOD_CLK	(0x3 << 10)
> > +
> > +/* IRCTRL_IR_BLASTER_ADDR3 */
> > +#define IRB_FIFO_THD_PENDING	BIT(16)
> > +#define IRB_FIFO_IRQ_ENABLE	BIT(8)
> > +
> > +struct meson_irtx {
> > +	struct device *dev;
> > +	void __iomem *reg_base;
> > +	u32 *buf;
> > +	unsigned int buf_len;
> > +	unsigned int buf_head;
> > +	unsigned int carrier;
> > +	unsigned int duty_cycle;
> > +	spinlock_t lock;
> > +	struct completion completion;
> > +	unsigned int fifo_threshold;
> > +	unsigned long clk_rate;
> > +};
> > +
> > +static void meson_irtx_set_mod(struct meson_irtx *ir)
> > +{
> > +	unsigned int cnt = DIV_ROUND_CLOSEST(ir->clk_rate,
> > ir->carrier);
> > +	unsigned int pulse_cnt = DIV_ROUND_CLOSEST(cnt *
> > ir->duty_cycle, 100);
> > +	unsigned int space_cnt = cnt - pulse_cnt;
> > +
> > +	dev_dbg(ir->dev, "F_mod = %uHz, T_mod = %luns, duty_cycle
> > = %u%%\n",
> > +		ir->carrier, NSEC_PER_SEC / ir->clk_rate * cnt,
> > +		100 * pulse_cnt / cnt);
> > +
> > +	writel(IRB_MOD_COUNT(pulse_cnt, space_cnt),
> > +	       ir->reg_base + IRB_ADDR1);
> > +}
> > +
> > +static void meson_irtx_setup(struct meson_irtx *ir, unsigned int
> > clk_nr) +{
> > +	/*
> > +	 * Disable the TX, set modulator clock tick and set
> > initialize
> > +	 * output to be high. Set up carrier frequency and duty
> > cycle. Then
> > +	 * unset initialize output. Enable FIFO interrupt, set
> > FIFO interrupt
> > +	 * threshold. Finally, enable the transmitter back.
> > +	 */
> > +	writel(~IRB_ENABLE & (IRB_MOD_CLK(clk_nr) | IRB_INIT_HIGH),
> > +	       ir->reg_base + IRB_ADDR0);
> > +	meson_irtx_set_mod(ir);
> > +	writel(readl(ir->reg_base + IRB_ADDR0) & ~IRB_INIT_HIGH,
> > +	       ir->reg_base + IRB_ADDR0);
> > +	writel(IRB_FIFO_IRQ_ENABLE | ir->fifo_threshold,
> > +	       ir->reg_base + IRB_ADDR3);
> > +	writel(readl(ir->reg_base + IRB_ADDR0) | IRB_ENABLE,
> > +	       ir->reg_base + IRB_ADDR0);
> > +}
> > +
> > +static u32 meson_irtx_prepare_pulse(struct meson_irtx *ir,
> > unsigned int time) +{
> > +	unsigned int delay;
> > +	unsigned int tb = IRB_TB_MOD_CLK;
> > +	unsigned int tb_us = DIV_ROUND_CLOSEST(USEC_PER_SEC,
> > ir->carrier); +
> > +	delay = (DIV_ROUND_CLOSEST(time, tb_us) - 1) &
> > IRB_DELAY_MASK; +
> > +	return ((IRB_WRITE_FIFO | IRB_MOD_ENABLE) | tb | delay);
> > +}
> > +
> > +static u32 meson_irtx_prepare_space(struct meson_irtx *ir,
> > unsigned int time) +{
> > +	unsigned int delay;
> > +	unsigned int tb = IRB_TB_100US;
> > +	unsigned int tb_us = 100;
> > +
> > +	if (time <= IRB_MAX_DELAY) {
> > +		tb = IRB_TB_1US;
> > +		tb_us = 1;
> > +	} else if (time <= 10 * IRB_MAX_DELAY) {
> > +		tb = IRB_TB_10US;
> > +		tb_us = 10;
> > +	} else if (time <= 100 * IRB_MAX_DELAY) {
> > +		tb = IRB_TB_100US;
> > +		tb_us = 100;
> > +	}
> > +
> > +	delay = (DIV_ROUND_CLOSEST(time, tb_us) - 1) &
> > IRB_DELAY_MASK; +
> > +	return ((IRB_WRITE_FIFO & ~IRB_MOD_ENABLE) | tb | delay);
> > +}
> > +
> > +static void meson_irtx_send_buffer(struct meson_irtx *ir)
> > +{
> > +	unsigned int nr = 0;
> > +	unsigned int max_fifo_level = IRB_FIFO_LEN -
> > ir->fifo_threshold; +
> > +	while (ir->buf_head < ir->buf_len && nr < max_fifo_level) {
> > +		writel(ir->buf[ir->buf_head], ir->reg_base +
> > IRB_ADDR2); +
> > +		ir->buf_head++;
> > +		nr++;
> > +	}
> > +}
> > +
> > +static bool meson_irtx_check_buf(struct meson_irtx *ir,
> > +			  unsigned int *buf, unsigned int len)
> > +{
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < len; i++) {
> > +		unsigned int max_tb_us;
> > +		/*
> > +		 * Max space timebase is 100 us.
> > +		 * Pulse timebase equals to carrier period.
> > +		 */
> > +		if (i % 2 == 0)
> > +			max_tb_us = USEC_PER_SEC / ir->carrier;
> > +		else
> > +			max_tb_us = 100;
> > +
> > +		if (buf[i] >= max_tb_us * IRB_MAX_DELAY)
> > +			return false;
> > +	}
> > +
> > +	return true;
> > +}
> > +
> > +static void meson_irtx_fill_buf(struct meson_irtx *ir, u32
> > *dst_buf,
> > +				unsigned int *src_buf, unsigned
> > int len) +{
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < len; i++) {
> > +		if (i % 2 == 0)
> > +			dst_buf[i] = meson_irtx_prepare_pulse(ir,
> > src_buf[i]);
> > +		else
> > +			dst_buf[i] = meson_irtx_prepare_space(ir,
> > src_buf[i]);
> > +	}
> > +}
> > +
> > +static irqreturn_t meson_irtx_irqhandler(int irq, void *data)
> > +{
> > +	unsigned long flags;
> > +	struct meson_irtx *ir = data;
> > +
> > +	writel(readl(ir->reg_base + IRB_ADDR3) &
> > ~IRB_FIFO_THD_PENDING,
> > +	       ir->reg_base + IRB_ADDR3);
> > +
> > +	if (completion_done(&ir->completion))
> > +		return IRQ_HANDLED;
> > +
> > +	spin_lock_irqsave(&ir->lock, flags);
> > +	if (ir->buf_head < ir->buf_len)
> > +		meson_irtx_send_buffer(ir);
> > +	else
> > +		complete(&ir->completion);
> > +	spin_unlock_irqrestore(&ir->lock, flags);
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int meson_irtx_set_carrier(struct rc_dev *rc, u32 carrier)
> > +{
> > +	struct meson_irtx *ir = rc->priv;
> > +
> > +	if (carrier == 0)
> > +		return -EINVAL;
> > +
> > +	ir->carrier = carrier;
> > +	meson_irtx_set_mod(ir);
> > +
> > +	return 0;
> > +}
> > +
> > +static int meson_irtx_set_duty_cycle(struct rc_dev *rc, u32
> > duty_cycle) +{
> > +	struct meson_irtx *ir = rc->priv;
> > +
> > +	ir->duty_cycle = duty_cycle;
> > +	meson_irtx_set_mod(ir);
> > +
> > +	return 0;
> > +}
> > +
> > +static void meson_irtx_update_buf(struct meson_irtx *ir, u32 *buf,
> > +				  unsigned int len, unsigned int
> > head) +{
> > +	ir->buf = buf;
> > +	ir->buf_len = len;
> > +	ir->buf_head = head;
> > +}
> > +
> > +static int meson_irtx_transmit(struct rc_dev *rc, unsigned int
> > *buf,
> > +			       unsigned int len)
> > +{
> > +	unsigned long flags;
> > +	struct meson_irtx *ir = rc->priv;
> > +	u32 *tx_buf;
> > +	int ret = len;
> > +
> > +	if (!meson_irtx_check_buf(ir, buf, len))
> > +		return -EINVAL;
> > +
> > +	tx_buf = kmalloc_array(len, sizeof(u32), GFP_KERNEL);
> > +	if (!tx_buf)
> > +		return -ENOMEM;
> > +
> > +	meson_irtx_fill_buf(ir, tx_buf, buf, len);
> > +	dev_dbg(ir->dev, "TX buffer filled, length = %u\n", len);
> > +
> > +	spin_lock_irqsave(&ir->lock, flags);
> > +	meson_irtx_update_buf(ir, tx_buf, len, 0);
> > +	reinit_completion(&ir->completion);
> > +	meson_irtx_send_buffer(ir);
> > +	spin_unlock_irqrestore(&ir->lock, flags);
> > +
> > +	if (!wait_for_completion_timeout(&ir->completion,
> > +
> > usecs_to_jiffies(MIRTX_TIMEOUT_US)))
> > +		ret = -ETIMEDOUT;
> > +
> > +	spin_lock_irqsave(&ir->lock, flags);
> > +	kfree(ir->buf);
> > +	meson_irtx_update_buf(ir, NULL, 0, 0);
> > +	spin_unlock_irqrestore(&ir->lock, flags);
> > +
> > +	return ret;
> > +}
> > +
> > +static int meson_irtx_mod_clock_probe(struct meson_irtx *ir,
> > +				      unsigned int *clk_nr)
> > +{
> > +	struct device_node *np = ir->dev->of_node;
> > +	struct clk *clock;
> > +
> > +	if (!np)
> > +		return -ENODEV;
> > +
> > +	clock = devm_clk_get(ir->dev, "xtal");
> > +	if (IS_ERR(clock) || clk_prepare_enable(clock))
> > +		return -ENODEV;
> > +
> > +	*clk_nr = IRB_MOD_XTAL3_CLK;
> > +	ir->clk_rate = clk_get_rate(clock) / 3;
> > +
> > +	if (ir->clk_rate < IRB_MOD_1US_CLK_RATE) {
> > +		*clk_nr = IRB_MOD_1US_CLK;
> > +		ir->clk_rate = IRB_MOD_1US_CLK_RATE;
> > +	}
> > +
> > +	dev_info(ir->dev, "F_clk = %luHz\n", ir->clk_rate);
> > +
> > +	return 0;
> > +}
> > +
> > +static int __init meson_irtx_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	struct meson_irtx *ir;
> > +	struct rc_dev *rc;
> > +	int irq;
> > +	unsigned int clk_nr;
> > +	int ret;
> > +
> > +	ir = devm_kzalloc(dev, sizeof(*ir), GFP_KERNEL);
> > +	if (!ir)
> > +		return -ENOMEM;
> > +
> > +	ir->reg_base = devm_platform_ioremap_resource(pdev, 0);
> > +	if (IS_ERR(ir->reg_base))
> > +		return PTR_ERR(ir->reg_base);
> > +
> > +	irq = platform_get_irq(pdev, 0);
> > +	if (irq < 0) {
> > +		dev_err(dev, "no irq resource found\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	if (of_property_read_u32(dev->of_node,
> > "amlogic,fifo-threshold",
> > +				 &ir->fifo_threshold))
> > +		ir->fifo_threshold = MIRTX_DEFAULT_FIFO_THD;
> > +	else if (ir->fifo_threshold >= IRB_FIFO_LEN)
> > +		ir->fifo_threshold = MIRTX_DEFAULT_FIFO_THD;
> > +	dev_dbg(dev, "FIFO threshold set to %u\n",
> > ir->fifo_threshold); +
> > +	ir->dev = dev;
> > +	ir->carrier = MIRTX_DEFAULT_CARRIER;
> > +	ir->duty_cycle = MIRTX_DEFAULT_DUTY_CYCLE;
> > +	init_completion(&ir->completion);
> > +	spin_lock_init(&ir->lock);
> > +
> > +	ret = meson_irtx_mod_clock_probe(ir, &clk_nr);
> > +	if (ret) {
> > +		dev_err(dev, "modulator clock setup failed\n");
> > +		return ret;
> > +	}
> > +	meson_irtx_setup(ir, clk_nr);
> > +
> > +	ret = devm_request_irq(dev, irq,
> > +			       meson_irtx_irqhandler,
> > +			       IRQF_TRIGGER_RISING,
> > +			       DRIVER_NAME, ir);
> > +	if (ret) {
> > +		dev_err(dev, "irq request failed\n");
> > +		return ret;
> > +	}
> > +
> > +	rc = rc_allocate_device(RC_DRIVER_IR_RAW_TX);
> > +	if (!rc)
> > +		return -ENOMEM;
> > +
> > +	rc->driver_name = DRIVER_NAME;
> > +	rc->device_name = DEVICE_NAME;
> > +	rc->priv = ir;
> > +
> > +	rc->tx_ir = meson_irtx_transmit;
> > +	rc->s_tx_carrier = meson_irtx_set_carrier;
> > +	rc->s_tx_duty_cycle = meson_irtx_set_duty_cycle;
> > +
> > +	ret = rc_register_device(rc);
> > +	if (ret < 0) {
> > +		dev_err(dev, "rc_dev registration failed\n");
> > +		rc_free_device(rc);
> > +		return ret;
> > +	}
> > +
> > +	platform_set_drvdata(pdev, rc);
> > +
> > +	return 0;
> > +}
> > +
> > +static int meson_irtx_remove(struct platform_device *pdev)
> > +{
> > +	struct rc_dev *rc = platform_get_drvdata(pdev);
> > +
> > +	rc_unregister_device(rc);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct of_device_id meson_irtx_dt_match[] = {
> > +	{
> > +		.compatible = "amlogic,meson-g12a-ir-tx",
> > +	},
> > +	{},
> > +};
> > +MODULE_DEVICE_TABLE(of, meson_irtx_dt_match);
> > +
> > +static struct platform_driver meson_irtx_pd = {
> > +	.remove = meson_irtx_remove,
> > +	.driver = {
> > +		.name = DRIVER_NAME,
> > +		.owner  = THIS_MODULE,
> > +		.of_match_table = meson_irtx_dt_match,
> > +	},
> > +};
> > +
> > +module_platform_driver_probe(meson_irtx_pd, meson_irtx_probe);
> > +
> > +MODULE_DESCRIPTION("Meson IR TX driver");
> > +MODULE_AUTHOR("Viktor Prutyanov <viktor.prutyanov@phystech.edu>");
> > +MODULE_LICENSE("GPL");
> > -- 
> > 2.21.0  

Best regards,
Viktor