counter: 104-quad-8: Replace mutex with spinlock

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>

diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
index c587f295d720e62d1c099ffec707407240368cc5..a56751bf1e9b75606c8675110d272fd55b38ad5f 100644 (file)
--- a/drivers/counter/104-quad-8.c
+++ b/drivers/counter/104-quad-8.c
@@ -16,6 +16,7 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/types.h>
+#include <linux/spinlock.h>
 
 #define QUAD8_EXTENT 32
 
@@ -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];
@@ -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);
@@ -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,
@@ -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;
 }
@@ -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);
@@ -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;
 }
@@ -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]) {
@@ -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;
 }
@@ -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;
@@ -272,7 +277,7 @@ 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;
                }
        }
@@ -280,7 +285,7 @@ static int quad8_function_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;
 }
@@ -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];
 
@@ -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;
 }
@@ -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;
        }
 
@@ -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;
 }
@@ -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) {
@@ -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;
 
@@ -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;
 }
@@ -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;
 
@@ -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;
 }
@@ -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;
 }
@@ -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]) {
@@ -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;
 }
@@ -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;
 }
@@ -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;
 
@@ -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;
 }
@@ -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));
@@ -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);
@@ -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;
 }
@@ -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;
 
@@ -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;
 }
@@ -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);