Message-ID: <20210711144449.65cf28d9@jic23-huawei>
Date:   Sun, 11 Jul 2021 14:44:49 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     William Breathitt Gray <vilhelm.gray@...il.com>
Cc:     linux-stm32@...md-mailman.stormreply.com, kernel@...gutronix.de,
        a.fatoum@...gutronix.de, kamel.bouhara@...tlin.com,
        gwendal@...omium.org, alexandre.belloni@...tlin.com,
        david@...hnology.com, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        syednwaris@...il.com, patrick.havelange@...ensium.com,
        fabrice.gasnier@...com, mcoquelin.stm32@...il.com,
        alexandre.torgue@...com, o.rempel@...gutronix.de,
        jarkko.nikula@...ux.intel.com
Subject: Re: [PATCH v12 17/17] counter: 104-quad-8: Add IRQ support for the
 ACCES 104-QUAD-8

On Mon,  5 Jul 2021 17:19:05 +0900
William Breathitt Gray <vilhelm.gray@...il.com> wrote:

> The LSI/CSI LS7266R1 chip provides programmable output via the FLG pins.
> When interrupts are enabled on the ACCES 104-QUAD-8, they occur whenever
> FLG1 is active. Four functions are available for the FLG1 signal: Carry,
> Compare, Carry-Borrow, and Index.
> 
> 	Carry:
> 		Interrupt generated on active low Carry signal. Carry
> 		signal toggles every time the respective channel's
> 		counter overflows.
> 
> 	Compare:
> 		Interrupt generated on active low Compare signal.
> 		Compare signal toggles every time respective channel's
> 		preset register is equal to the respective channel's
> 		counter.
> 
> 	Carry-Borrow:
> 		Interrupt generated on active low Carry signal and
> 		active low Borrow signal. Carry signal toggles every
> 		time the respective channel's counter overflows. Borrow
> 		signal toggles every time the respective channel's
> 		counter underflows.
> 
> 	Index:
> 		Interrupt generated on active high Index signal.
> 
> These four functions correspond respectivefly to the following four
> Counter event types: COUNTER_EVENT_OVERFLOW, COUNTER_EVENT_THRESHOLD,
> COUNTER_EVENT_OVERFLOW_UNDERFLOW, and COUNTER_EVENT_INDEX. Interrupts
> push Counter events to event channel X, where 'X' is the respective
> channel whose FLG1 activated.
> 
> This patch adds IRQ support for the ACCES 104-QUAD-8. The interrupt line
> numbers for the devices may be configured via the irq array module
> parameter.
> 
> Acked-by: Syed Nayyar Waris <syednwaris@...il.com>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@...il.com>

Trivial comment inline.

> ---
>  drivers/counter/104-quad-8.c | 167 +++++++++++++++++++++++++++++++++--
>  drivers/counter/Kconfig      |   6 +-
>  2 files changed, 164 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> index a56751bf1e9b..1cbd60aaed69 100644
> --- a/drivers/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -11,6 +11,7 @@
>  #include <linux/errno.h>
>  #include <linux/io.h>
>  #include <linux/ioport.h>
> +#include <linux/interrupt.h>
>  #include <linux/isa.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> @@ -25,6 +26,10 @@ static unsigned int num_quad8;
>  module_param_hw_array(base, uint, ioport, &num_quad8, 0);
>  MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
>  
> +static unsigned int irq[max_num_isa_dev(QUAD8_EXTENT)];
> +module_param_hw_array(irq, uint, irq, NULL, 0);
> +MODULE_PARM_DESC(irq, "ACCES 104-QUAD-8 interrupt line numbers");
> +
>  #define QUAD8_NUM_COUNTERS 8
>  
>  /**
> @@ -38,6 +43,8 @@ MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
>   * @quadrature_scale:	array of quadrature mode scale configurations
>   * @ab_enable:		array of A and B inputs enable configurations
>   * @preset_enable:	array of set_to_preset_on_index attribute configurations
> + * @irq_trigger:	array of current IRQ trigger function configurations
> + * @next_irq_trigger:	array of next IRQ trigger function configurations
>   * @synchronous_mode:	array of index function synchronous mode configurations
>   * @index_polarity:	array of index function polarity configurations
>   * @cable_fault_enable:	differential encoder cable status enable configurations
> @@ -53,13 +60,17 @@ struct quad8 {
>  	unsigned int quadrature_scale[QUAD8_NUM_COUNTERS];
>  	unsigned int ab_enable[QUAD8_NUM_COUNTERS];
>  	unsigned int preset_enable[QUAD8_NUM_COUNTERS];
> +	unsigned int irq_trigger[QUAD8_NUM_COUNTERS];
> +	unsigned int next_irq_trigger[QUAD8_NUM_COUNTERS];
>  	unsigned int synchronous_mode[QUAD8_NUM_COUNTERS];
>  	unsigned int index_polarity[QUAD8_NUM_COUNTERS];
>  	unsigned int cable_fault_enable;
>  	unsigned int base;
>  };
>  
> +#define QUAD8_REG_INTERRUPT_STATUS 0x10
>  #define QUAD8_REG_CHAN_OP 0x11
> +#define QUAD8_REG_INDEX_INTERRUPT 0x12
>  #define QUAD8_REG_INDEX_INPUT_LEVELS 0x16
>  #define QUAD8_DIFF_ENCODER_CABLE_STATUS 0x17
>  /* Borrow Toggle flip-flop */
> @@ -92,8 +103,8 @@ struct quad8 {
>  #define QUAD8_RLD_CNTR_OUT 0x10
>  /* Transfer Preset Register LSB to FCK Prescaler */
>  #define QUAD8_RLD_PRESET_PSC 0x18
> -#define QUAD8_CHAN_OP_ENABLE_COUNTERS 0x00
>  #define QUAD8_CHAN_OP_RESET_COUNTERS 0x01
> +#define QUAD8_CHAN_OP_ENABLE_INTERRUPT_FUNC 0x04
>  #define QUAD8_CMR_QUADRATURE_X1 0x08
>  #define QUAD8_CMR_QUADRATURE_X2 0x10
>  #define QUAD8_CMR_QUADRATURE_X4 0x18
> @@ -378,13 +389,103 @@ static int quad8_action_read(struct counter_device *counter,
>  	}
>  }
>  
> +enum {
> +	QUAD8_EVENT_NONE = -1,
> +	QUAD8_EVENT_CARRY = 0,
> +	QUAD8_EVENT_COMPARE = 1,
> +	QUAD8_EVENT_CARRY_BORROW = 2,
> +	QUAD8_EVENT_INDEX = 3,
> +};
> +
> +static int quad8_events_configure(struct counter_device *counter)
> +{
> +	struct quad8 *const priv = counter->priv;
> +	unsigned long irq_enabled = 0;
> +	unsigned long irqflags;
> +	size_t channel;
> +	unsigned long ior_cfg;
> +	unsigned long base_offset;
> +
> +	spin_lock_irqsave(&priv->lock, irqflags);
> +
> +	/* Enable interrupts for the requested channels, disable for the rest */
> +	for (channel = 0; channel < QUAD8_NUM_COUNTERS; channel++) {
> +		if (priv->next_irq_trigger[channel] == QUAD8_EVENT_NONE)
> +			continue;
> +
> +		if (priv->irq_trigger[channel] != priv->next_irq_trigger[channel]) {
> +			/* Save new IRQ function configuration */
> +			priv->irq_trigger[channel] = priv->next_irq_trigger[channel];
> +
> +			/* Load configuration to I/O Control Register */
> +			ior_cfg = priv->ab_enable[channel] |
> +				  priv->preset_enable[channel] << 1 |
> +				  priv->irq_trigger[channel] << 3;

Nicer to define masks and use FIELD_PREP etc for these rather than hiding shifts
down here in the code.

> +			base_offset = priv->base + 2 * channel + 1;
> +			outb(QUAD8_CTR_IOR | ior_cfg, base_offset);
> +		}
> +
> +		/* Reset next IRQ trigger function configuration */
> +		priv->next_irq_trigger[channel] = QUAD8_EVENT_NONE;
> +
> +		/* Enable IRQ line */
> +		irq_enabled |= BIT(channel);
> +	}
> +
> +	outb(irq_enabled, priv->base + QUAD8_REG_INDEX_INTERRUPT);
> +
> +	spin_unlock_irqrestore(&priv->lock, irqflags);
> +
> +	return 0;
> +}
> +
> +static int quad8_watch_validate(struct counter_device *counter,
> +				const struct counter_watch *watch)
> +{
> +	struct quad8 *const priv = counter->priv;
> +
> +	if (watch->channel > QUAD8_NUM_COUNTERS - 1)
> +		return -EINVAL;
> +
> +	switch (watch->event) {
> +	case COUNTER_EVENT_OVERFLOW:
> +		if (priv->next_irq_trigger[watch->channel] == QUAD8_EVENT_NONE)
> +			priv->next_irq_trigger[watch->channel] = QUAD8_EVENT_CARRY;
> +		else if (priv->next_irq_trigger[watch->channel] != QUAD8_EVENT_CARRY)
> +			return -EINVAL;
> +		return 0;
> +	case COUNTER_EVENT_THRESHOLD:
> +		if (priv->next_irq_trigger[watch->channel] == QUAD8_EVENT_NONE)
> +			priv->next_irq_trigger[watch->channel] = QUAD8_EVENT_COMPARE;
> +		else if (priv->next_irq_trigger[watch->channel] != QUAD8_EVENT_COMPARE)
> +			return -EINVAL;
> +		return 0;
> +	case COUNTER_EVENT_OVERFLOW_UNDERFLOW:
> +		if (priv->next_irq_trigger[watch->channel] == QUAD8_EVENT_NONE)
> +			priv->next_irq_trigger[watch->channel] = QUAD8_EVENT_CARRY_BORROW;
> +		else if (priv->next_irq_trigger[watch->channel] != QUAD8_EVENT_CARRY_BORROW)
> +			return -EINVAL;
> +		return 0;
> +	case COUNTER_EVENT_INDEX:
> +		if (priv->next_irq_trigger[watch->channel] == QUAD8_EVENT_NONE)
> +			priv->next_irq_trigger[watch->channel] = QUAD8_EVENT_INDEX;
> +		else if (priv->next_irq_trigger[watch->channel] != QUAD8_EVENT_INDEX)
> +			return -EINVAL;
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
>  static const struct counter_ops quad8_ops = {
>  	.signal_read = quad8_signal_read,
>  	.count_read = quad8_count_read,
>  	.count_write = quad8_count_write,
>  	.function_read = quad8_function_read,
>  	.function_write = quad8_function_write,
> -	.action_read = quad8_action_read
> +	.action_read = quad8_action_read,
> +	.events_configure = quad8_events_configure,
> +	.watch_validate = quad8_watch_validate,
>  };
>  
>  static const char *const quad8_index_polarity_modes[] = {
> @@ -579,7 +680,8 @@ static int quad8_count_enable_write(struct counter_device *counter,
>  
>  	priv->ab_enable[count->id] = enable;
>  
> -	ior_cfg = enable | priv->preset_enable[count->id] << 1;
> +	ior_cfg = enable | priv->preset_enable[count->id] << 1 |
> +		  priv->irq_trigger[count->id] << 3;
>  
>  	/* Load I/O control configuration */
>  	outb(QUAD8_CTR_IOR | ior_cfg, base_offset + 1);
> @@ -728,7 +830,8 @@ static int quad8_count_preset_enable_write(struct counter_device *counter,
>  
>  	priv->preset_enable[count->id] = preset_enable;
>  
> -	ior_cfg = priv->ab_enable[count->id] | preset_enable << 1;
> +	ior_cfg = priv->ab_enable[count->id] | preset_enable << 1 |
> +		  priv->irq_trigger[count->id] << 3;
>  
>  	/* Load I/O control configuration to Input / Output Control Register */
>  	outb(QUAD8_CTR_IOR | ior_cfg, base_offset);
> @@ -980,11 +1083,54 @@ static struct counter_count quad8_counts[] = {
>  	QUAD8_COUNT(7, "Channel 8 Count")
>  };
>  
> +static irqreturn_t quad8_irq_handler(int irq, void *private)
> +{
> +	struct quad8 *const priv = private;
> +	const unsigned long base = priv->base;
> +	unsigned long irq_status;
> +	unsigned long channel;
> +	u8 event;
> +
> +	irq_status = inb(base + QUAD8_REG_INTERRUPT_STATUS);
> +	if (!irq_status)
> +		return IRQ_NONE;
> +
> +	for_each_set_bit(channel, &irq_status, QUAD8_NUM_COUNTERS) {
> +		switch (priv->irq_trigger[channel]) {
> +		case QUAD8_EVENT_CARRY:
> +			event = COUNTER_EVENT_OVERFLOW;
> +				break;
> +		case QUAD8_EVENT_COMPARE:
> +			event = COUNTER_EVENT_THRESHOLD;
> +				break;
> +		case QUAD8_EVENT_CARRY_BORROW:
> +			event = COUNTER_EVENT_OVERFLOW_UNDERFLOW;
> +				break;
> +		case QUAD8_EVENT_INDEX:
> +			event = COUNTER_EVENT_INDEX;
> +				break;
> +		default:
> +			/* should never reach this path */
> +			WARN_ONCE(true, "invalid interrupt trigger function %u configured for channel %lu\n",
> +				  priv->irq_trigger[channel], channel);
> +			continue;
> +		}
> +
> +		counter_push_event(&priv->counter, event, channel);
> +	}
> +
> +	/* Clear pending interrupts on device */
> +	outb(QUAD8_CHAN_OP_ENABLE_INTERRUPT_FUNC, base + QUAD8_REG_CHAN_OP);
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static int quad8_probe(struct device *dev, unsigned int id)
>  {
>  	struct quad8 *priv;
>  	int i, j;
>  	unsigned int base_offset;
> +	int err;
>  
>  	if (!devm_request_region(dev, base[id], QUAD8_EXTENT, dev_name(dev))) {
>  		dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
> @@ -1009,6 +1155,8 @@ static int quad8_probe(struct device *dev, unsigned int id)
>  
>  	spin_lock_init(&priv->lock);
>  
> +	/* Reset Index/Interrupt Register */
> +	outb(0x00, base[id] + QUAD8_REG_INDEX_INTERRUPT);
>  	/* Reset all counters and disable interrupt function */
>  	outb(QUAD8_CHAN_OP_RESET_COUNTERS, base[id] + QUAD8_REG_CHAN_OP);
>  	/* Set initial configuration for all counters */
> @@ -1035,11 +1183,18 @@ static int quad8_probe(struct device *dev, unsigned int id)
>  		outb(QUAD8_CTR_IOR, base_offset + 1);
>  		/* Disable index function; negative index polarity */
>  		outb(QUAD8_CTR_IDR, base_offset + 1);
> +		/* Initialize next IRQ trigger function configuration */
> +		priv->next_irq_trigger[i] = QUAD8_EVENT_NONE;
>  	}
>  	/* Disable Differential Encoder Cable Status for all channels */
>  	outb(0xFF, base[id] + QUAD8_DIFF_ENCODER_CABLE_STATUS);
> -	/* Enable all counters */
> -	outb(QUAD8_CHAN_OP_ENABLE_COUNTERS, base[id] + QUAD8_REG_CHAN_OP);
> +	/* Enable all counters and enable interrupt function */
> +	outb(QUAD8_CHAN_OP_ENABLE_INTERRUPT_FUNC, base[id] + QUAD8_REG_CHAN_OP);
> +
> +	err = devm_request_irq(dev, irq[id], quad8_irq_handler, IRQF_SHARED,
> +			       priv->counter.name, priv);
> +	if (err)
> +		return err;
>  
>  	return devm_counter_register(dev, &priv->counter);
>  }
> diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
> index d5d2540b30c2..3dcdb681c4e4 100644
> --- a/drivers/counter/Kconfig
> +++ b/drivers/counter/Kconfig
> @@ -23,11 +23,11 @@ config 104_QUAD_8
>  	  A counter's respective error flag may be cleared by performing a write
>  	  operation on the respective count value attribute. Although the
>  	  104-QUAD-8 counters have a 25-bit range, only the lower 24 bits may be
> -	  set, either directly or via the counter's preset attribute. Interrupts
> -	  are not supported by this driver.
> +	  set, either directly or via the counter's preset attribute.
>  
>  	  The base port addresses for the devices may be configured via the base
> -	  array module parameter.
> +	  array module parameter. The interrupt line numbers for the devices may
> +	  be configured via the irq array module parameter.
>  
>  config INTERRUPT_CNT
>  	tristate "Interrupt counter driver"

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