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counter: 104-quad-8: Replace mutex with spinlock
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This patch replaces the mutex I/O lock with a spinlock. This is in
preparation for a subsequent patch adding IRQ support for 104-QUAD-8
devices; we can't sleep in an interrupt context, so we'll need to use a
spinlock instead.

Acked-by: Syed Nayyar Waris <syednwaris@gmail.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/3f74491dec66de10d062978bcb7b9c2b3bdea86c.1632884256.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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William Breathitt Gray authored and Jonathan Cameron committed Oct 17, 2021
1 parent feff17a commit 09db467
Showing 1 changed file with 52 additions and 37 deletions.
89 changes: 52 additions & 37 deletions drivers/counter/104-quad-8.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/spinlock.h>

#define QUAD8_EXTENT 32

Expand Down Expand Up @@ -43,7 +44,7 @@ MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
* @base: base port address of the device
*/
struct quad8 {
struct mutex lock;
spinlock_t lock;
struct counter_device counter;
unsigned int fck_prescaler[QUAD8_NUM_COUNTERS];
unsigned int preset[QUAD8_NUM_COUNTERS];
Expand Down Expand Up @@ -124,6 +125,7 @@ static int quad8_count_read(struct counter_device *counter,
unsigned int flags;
unsigned int borrow;
unsigned int carry;
unsigned long irqflags;
int i;

flags = inb(base_offset + 1);
Expand All @@ -133,7 +135,7 @@ static int quad8_count_read(struct counter_device *counter,
/* Borrow XOR Carry effectively doubles count range */
*val = (unsigned long)(borrow ^ carry) << 24;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

/* Reset Byte Pointer; transfer Counter to Output Latch */
outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_CNTR_OUT,
Expand All @@ -142,7 +144,7 @@ static int quad8_count_read(struct counter_device *counter,
for (i = 0; i < 3; i++)
*val |= (unsigned long)inb(base_offset) << (8 * i);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand All @@ -152,13 +154,14 @@ static int quad8_count_write(struct counter_device *counter,
{
struct quad8 *const priv = counter->priv;
const int base_offset = priv->base + 2 * count->id;
unsigned long irqflags;
int i;

/* Only 24-bit values are supported */
if (val > 0xFFFFFF)
return -ERANGE;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

/* Reset Byte Pointer */
outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP, base_offset + 1);
Expand All @@ -183,7 +186,7 @@ static int quad8_count_write(struct counter_device *counter,
/* Reset Error flag */
outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_E, base_offset + 1);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand All @@ -201,8 +204,9 @@ static int quad8_function_read(struct counter_device *counter,
{
struct quad8 *const priv = counter->priv;
const int id = count->id;
unsigned long irqflags;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

if (priv->quadrature_mode[id])
switch (priv->quadrature_scale[id]) {
Expand All @@ -219,7 +223,7 @@ static int quad8_function_read(struct counter_device *counter,
else
*function = COUNTER_FUNCTION_PULSE_DIRECTION;

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand All @@ -234,10 +238,11 @@ static int quad8_function_write(struct counter_device *counter,
unsigned int *const scale = priv->quadrature_scale + id;
unsigned int *const synchronous_mode = priv->synchronous_mode + id;
const int base_offset = priv->base + 2 * id + 1;
unsigned long irqflags;
unsigned int mode_cfg;
unsigned int idr_cfg;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

mode_cfg = priv->count_mode[id] << 1;
idr_cfg = priv->index_polarity[id] << 1;
Expand Down Expand Up @@ -272,15 +277,15 @@ static int quad8_function_write(struct counter_device *counter,
break;
default:
/* should never reach this path */
mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);
return -EINVAL;
}
}

/* Load mode configuration to Counter Mode Register */
outb(QUAD8_CTR_CMR | mode_cfg, base_offset);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand Down Expand Up @@ -406,9 +411,10 @@ static int quad8_index_polarity_set(struct counter_device *counter,
struct quad8 *const priv = counter->priv;
const size_t channel_id = signal->id - 16;
const int base_offset = priv->base + 2 * channel_id + 1;
unsigned long irqflags;
unsigned int idr_cfg = index_polarity << 1;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

idr_cfg |= priv->synchronous_mode[channel_id];

Expand All @@ -417,7 +423,7 @@ static int quad8_index_polarity_set(struct counter_device *counter,
/* Load Index Control configuration to Index Control Register */
outb(QUAD8_CTR_IDR | idr_cfg, base_offset);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand Down Expand Up @@ -446,15 +452,16 @@ static int quad8_synchronous_mode_set(struct counter_device *counter,
struct quad8 *const priv = counter->priv;
const size_t channel_id = signal->id - 16;
const int base_offset = priv->base + 2 * channel_id + 1;
unsigned long irqflags;
unsigned int idr_cfg = synchronous_mode;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

idr_cfg |= priv->index_polarity[channel_id] << 1;

/* Index function must be non-synchronous in non-quadrature mode */
if (synchronous_mode && !priv->quadrature_mode[channel_id]) {
mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);
return -EINVAL;
}

Expand All @@ -463,7 +470,7 @@ static int quad8_synchronous_mode_set(struct counter_device *counter,
/* Load Index Control configuration to Index Control Register */
outb(QUAD8_CTR_IDR | idr_cfg, base_offset);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand Down Expand Up @@ -510,6 +517,7 @@ static int quad8_count_mode_write(struct counter_device *counter,
unsigned int count_mode;
unsigned int mode_cfg;
const int base_offset = priv->base + 2 * count->id + 1;
unsigned long irqflags;

/* Map Generic Counter count mode to 104-QUAD-8 count mode */
switch (cnt_mode) {
Expand All @@ -530,7 +538,7 @@ static int quad8_count_mode_write(struct counter_device *counter,
return -EINVAL;
}

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

priv->count_mode[count->id] = count_mode;

Expand All @@ -544,7 +552,7 @@ static int quad8_count_mode_write(struct counter_device *counter,
/* Load mode configuration to Counter Mode Register */
outb(QUAD8_CTR_CMR | mode_cfg, base_offset);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand All @@ -564,9 +572,10 @@ static int quad8_count_enable_write(struct counter_device *counter,
{
struct quad8 *const priv = counter->priv;
const int base_offset = priv->base + 2 * count->id;
unsigned long irqflags;
unsigned int ior_cfg;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

priv->ab_enable[count->id] = enable;

Expand All @@ -575,7 +584,7 @@ static int quad8_count_enable_write(struct counter_device *counter,
/* Load I/O control configuration */
outb(QUAD8_CTR_IOR | ior_cfg, base_offset + 1);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand Down Expand Up @@ -626,16 +635,17 @@ static int quad8_count_preset_write(struct counter_device *counter,
struct counter_count *count, u64 preset)
{
struct quad8 *const priv = counter->priv;
unsigned long irqflags;

/* Only 24-bit values are supported */
if (preset > 0xFFFFFF)
return -ERANGE;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

quad8_preset_register_set(priv, count->id, preset);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand All @@ -644,8 +654,9 @@ static int quad8_count_ceiling_read(struct counter_device *counter,
struct counter_count *count, u64 *ceiling)
{
struct quad8 *const priv = counter->priv;
unsigned long irqflags;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

/* Range Limit and Modulo-N count modes use preset value as ceiling */
switch (priv->count_mode[count->id]) {
Expand All @@ -659,7 +670,7 @@ static int quad8_count_ceiling_read(struct counter_device *counter,
break;
}

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand All @@ -668,23 +679,24 @@ static int quad8_count_ceiling_write(struct counter_device *counter,
struct counter_count *count, u64 ceiling)
{
struct quad8 *const priv = counter->priv;
unsigned long irqflags;

/* Only 24-bit values are supported */
if (ceiling > 0xFFFFFF)
return -ERANGE;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

/* Range Limit and Modulo-N count modes use preset value as ceiling */
switch (priv->count_mode[count->id]) {
case 1:
case 3:
quad8_preset_register_set(priv, count->id, ceiling);
mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);
return 0;
}

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return -EINVAL;
}
Expand All @@ -706,12 +718,13 @@ static int quad8_count_preset_enable_write(struct counter_device *counter,
{
struct quad8 *const priv = counter->priv;
const int base_offset = priv->base + 2 * count->id + 1;
unsigned long irqflags;
unsigned int ior_cfg;

/* Preset enable is active low in Input/Output Control register */
preset_enable = !preset_enable;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

priv->preset_enable[count->id] = preset_enable;

Expand All @@ -720,7 +733,7 @@ static int quad8_count_preset_enable_write(struct counter_device *counter,
/* Load I/O control configuration to Input / Output Control Register */
outb(QUAD8_CTR_IOR | ior_cfg, base_offset);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand All @@ -731,22 +744,23 @@ static int quad8_signal_cable_fault_read(struct counter_device *counter,
{
struct quad8 *const priv = counter->priv;
const size_t channel_id = signal->id / 2;
unsigned long irqflags;
bool disabled;
unsigned int status;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

disabled = !(priv->cable_fault_enable & BIT(channel_id));

if (disabled) {
mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);
return -EINVAL;
}

/* Logic 0 = cable fault */
status = inb(priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

/* Mask respective channel and invert logic */
*cable_fault = !(status & BIT(channel_id));
Expand All @@ -772,9 +786,10 @@ static int quad8_signal_cable_fault_enable_write(struct counter_device *counter,
{
struct quad8 *const priv = counter->priv;
const size_t channel_id = signal->id / 2;
unsigned long irqflags;
unsigned int cable_fault_enable;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

if (enable)
priv->cable_fault_enable |= BIT(channel_id);
Expand All @@ -786,7 +801,7 @@ static int quad8_signal_cable_fault_enable_write(struct counter_device *counter,

outb(cable_fault_enable, priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand All @@ -809,8 +824,9 @@ static int quad8_signal_fck_prescaler_write(struct counter_device *counter,
struct quad8 *const priv = counter->priv;
const size_t channel_id = signal->id / 2;
const int base_offset = priv->base + 2 * channel_id;
unsigned long irqflags;

mutex_lock(&priv->lock);
spin_lock_irqsave(&priv->lock, irqflags);

priv->fck_prescaler[channel_id] = prescaler;

Expand All @@ -822,7 +838,7 @@ static int quad8_signal_fck_prescaler_write(struct counter_device *counter,
outb(QUAD8_CTR_RLD | QUAD8_RLD_RESET_BP | QUAD8_RLD_PRESET_PSC,
base_offset + 1);

mutex_unlock(&priv->lock);
spin_unlock_irqrestore(&priv->lock, irqflags);

return 0;
}
Expand Down Expand Up @@ -991,8 +1007,7 @@ static int quad8_probe(struct device *dev, unsigned int id)
priv->counter.priv = priv;
priv->base = base[id];

/* Initialize mutex */
mutex_init(&priv->lock);
spin_lock_init(&priv->lock);

/* Reset all counters and disable interrupt function */
outb(QUAD8_CHAN_OP_RESET_COUNTERS, base[id] + QUAD8_REG_CHAN_OP);
Expand Down

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