Re: [PATCH v12 17/17] counter: 104-quad-8: Add IRQ support for the ACCES 104-QUAD-8

From: Jonathan Cameron
Date: Sun Jul 11 2021 - 09:42:42 EST

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On Mon, 5 Jul 2021 17:19:05 +0900
William Breathitt Gray <vilhelm.gray@xxxxxxxxx> 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@xxxxxxxxx>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@xxxxxxxxx>

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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