diff mbox series

[2/3] gpio: 104-dio-48e: Add Counter/Timer support

Message ID dc4d0d5ca6ea28eda18815df114ecb21226cb345.1681665189.git.william.gray@linaro.org
State Superseded
Headers show
Series Add Intel 8254 Counter support | expand

Commit Message

William Breathitt Gray April 16, 2023, 5:36 p.m. UTC 
The 104-DIO-48E features an 8254 Counter/Timer chip providing three
counter/timers which can be used for frequency measurement, frequency
output, pulse width modulation, pulse width measurement, event count,
etc. The counter/timers use the same addresses as PPI 0 (addresses 0x0
to 0x3), so a raw_spinlock_t is used to synchronize operations between
the two regmap mappings to prevent clobbering.

Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
 drivers/gpio/Kconfig            |   1 +
 drivers/gpio/gpio-104-dio-48e.c | 127 ++++++++++++++++++++++++++++----
 2 files changed, 112 insertions(+), 16 deletions(-)

Comments

Linus Walleij May 20, 2023, 7:28 p.m. UTC | #1 
On Sun, Apr 16, 2023 at 7:37 PM William Breathitt Gray
<william.gray@linaro.org> wrote:

> The 104-DIO-48E features an 8254 Counter/Timer chip providing three
> counter/timers which can be used for frequency measurement, frequency
> output, pulse width modulation, pulse width measurement, event count,
> etc. The counter/timers use the same addresses as PPI 0 (addresses 0x0
> to 0x3), so a raw_spinlock_t is used to synchronize operations between
> the two regmap mappings to prevent clobbering.
>
> Signed-off-by: William Breathitt Gray <william.gray@linaro.org>

Very interesting development here.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij
William Breathitt Gray May 22, 2023, 4:44 p.m. UTC | #2 
On Sat, May 20, 2023 at 09:28:15PM +0200, Linus Walleij wrote:
> On Sun, Apr 16, 2023 at 7:37 PM William Breathitt Gray
> <william.gray@linaro.org> wrote:
> 
> > The 104-DIO-48E features an 8254 Counter/Timer chip providing three
> > counter/timers which can be used for frequency measurement, frequency
> > output, pulse width modulation, pulse width measurement, event count,
> > etc. The counter/timers use the same addresses as PPI 0 (addresses 0x0
> > to 0x3), so a raw_spinlock_t is used to synchronize operations between
> > the two regmap mappings to prevent clobbering.
> >
> > Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
> 
> Very interesting development here.
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> 
> Yours,
> Linus Walleij

With this patch, we should now have complete support for every feature
available on this device. A nice milestone as well after first
introducing basic GPIO support for the ACCES 104-DIO-48E in 2016.

Given that there is also Intel 8255 support, it would be fun to route
back one of the device's GPIO outputs into the Intel 8254 timer gate and
hook up a simple speaker; we could get some nice beep generation going
and party like it's 1989! B-)

William Breathitt Gray
diff mbox series

Patch

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index badbe0582318..1fcc1245f954 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -840,6 +840,7 @@  config GPIO_104_DIO_48E
 	select REGMAP_IRQ
 	select GPIOLIB_IRQCHIP
 	select GPIO_I8255
+	select I8254
 	help
 	  Enables GPIO support for the ACCES 104-DIO-48E series (104-DIO-48E,
 	  104-DIO-24E). The base port addresses for the devices may be
diff --git a/drivers/gpio/gpio-104-dio-48e.c b/drivers/gpio/gpio-104-dio-48e.c
index 000a56d5f1d7..2df33650cbf4 100644
--- a/drivers/gpio/gpio-104-dio-48e.c
+++ b/drivers/gpio/gpio-104-dio-48e.c
@@ -9,6 +9,7 @@ 
 #include <linux/bits.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/i8254.h>
 #include <linux/ioport.h>
 #include <linux/irq.h>
 #include <linux/isa.h>
@@ -16,6 +17,7 @@ 
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/regmap.h>
+#include <linux/spinlock.h>
 #include <linux/types.h>
 
 #include "gpio-i8255.h"
@@ -37,6 +39,8 @@  MODULE_PARM_DESC(irq, "ACCES 104-DIO-48E interrupt line numbers");
 
 #define DIO48E_ENABLE_INTERRUPT 0xB
 #define DIO48E_DISABLE_INTERRUPT DIO48E_ENABLE_INTERRUPT
+#define DIO48E_ENABLE_COUNTER_TIMER_ADDRESSING 0xD
+#define DIO48E_DISABLE_COUNTER_TIMER_ADDRESSING DIO48E_ENABLE_COUNTER_TIMER_ADDRESSING
 #define DIO48E_CLEAR_INTERRUPT 0xF
 
 #define DIO48E_NUM_PPI 2
@@ -75,18 +79,20 @@  static const struct regmap_access_table dio48e_precious_table = {
 	.yes_ranges = dio48e_precious_ranges,
 	.n_yes_ranges = ARRAY_SIZE(dio48e_precious_ranges),
 };
-static const struct regmap_config dio48e_regmap_config = {
-	.reg_bits = 8,
-	.reg_stride = 1,
-	.val_bits = 8,
-	.io_port = true,
-	.max_register = 0xF,
-	.wr_table = &dio48e_wr_table,
-	.rd_table = &dio48e_rd_table,
-	.volatile_table = &dio48e_volatile_table,
-	.precious_table = &dio48e_precious_table,
-	.cache_type = REGCACHE_FLAT,
-	.use_raw_spinlock = true,
+
+static const struct regmap_range pit_wr_ranges[] = {
+	regmap_reg_range(0x0, 0x3),
+};
+static const struct regmap_range pit_rd_ranges[] = {
+	regmap_reg_range(0x0, 0x2),
+};
+static const struct regmap_access_table pit_wr_table = {
+	.yes_ranges = pit_wr_ranges,
+	.n_yes_ranges = ARRAY_SIZE(pit_wr_ranges),
+};
+static const struct regmap_access_table pit_rd_table = {
+	.yes_ranges = pit_rd_ranges,
+	.n_yes_ranges = ARRAY_SIZE(pit_rd_ranges),
 };
 
 /* only bit 3 on each respective Port C supports interrupts */
@@ -102,14 +108,56 @@  static const struct regmap_irq dio48e_regmap_irqs[] = {
 
 /**
  * struct dio48e_gpio - GPIO device private data structure
+ * @lock:	synchronization lock to prevent I/O race conditions
  * @map:	Regmap for the device
+ * @regs:	virtual mapping for device registers
+ * @flags:	IRQ flags saved during locking
  * @irq_mask:	Current IRQ mask state on the device
  */
 struct dio48e_gpio {
+	raw_spinlock_t lock;
 	struct regmap *map;
+	void __iomem *regs;
+	unsigned long flags;
 	unsigned int irq_mask;
 };
 
+static void dio48e_regmap_lock(void *lock_arg) __acquires(&dio48egpio->lock)
+{
+	struct dio48e_gpio *const dio48egpio = lock_arg;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&dio48egpio->lock, flags);
+	dio48egpio->flags = flags;
+}
+
+static void dio48e_regmap_unlock(void *lock_arg) __releases(&dio48egpio->lock)
+{
+	struct dio48e_gpio *const dio48egpio = lock_arg;
+
+	raw_spin_unlock_irqrestore(&dio48egpio->lock, dio48egpio->flags);
+}
+
+static void pit_regmap_lock(void *lock_arg) __acquires(&dio48egpio->lock)
+{
+	struct dio48e_gpio *const dio48egpio = lock_arg;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&dio48egpio->lock, flags);
+	dio48egpio->flags = flags;
+
+	iowrite8(0x00, dio48egpio->regs + DIO48E_ENABLE_COUNTER_TIMER_ADDRESSING);
+}
+
+static void pit_regmap_unlock(void *lock_arg) __releases(&dio48egpio->lock)
+{
+	struct dio48e_gpio *const dio48egpio = lock_arg;
+
+	ioread8(dio48egpio->regs + DIO48E_DISABLE_COUNTER_TIMER_ADDRESSING);
+
+	raw_spin_unlock_irqrestore(&dio48egpio->lock, dio48egpio->flags);
+}
+
 static int dio48e_handle_mask_sync(const int index,
 				   const unsigned int mask_buf_def,
 				   const unsigned int mask_buf,
@@ -176,6 +224,9 @@  static int dio48e_probe(struct device *dev, unsigned int id)
 	struct i8255_regmap_config config = {};
 	void __iomem *regs;
 	struct regmap *map;
+	struct regmap_config dio48e_regmap_config;
+	struct regmap_config pit_regmap_config;
+	struct i8254_regmap_config pit_config;
 	int err;
 	struct regmap_irq_chip *chip;
 	struct dio48e_gpio *dio48egpio;
@@ -187,21 +238,58 @@  static int dio48e_probe(struct device *dev, unsigned int id)
 		return -EBUSY;
 	}
 
+	dio48egpio = devm_kzalloc(dev, sizeof(*dio48egpio), GFP_KERNEL);
+	if (!dio48egpio)
+		return -ENOMEM;
+
 	regs = devm_ioport_map(dev, base[id], DIO48E_EXTENT);
 	if (!regs)
 		return -ENOMEM;
 
+	dio48egpio->regs = regs;
+
+	raw_spin_lock_init(&dio48egpio->lock);
+
+	dio48e_regmap_config = (struct regmap_config) {
+		.reg_bits = 8,
+		.reg_stride = 1,
+		.val_bits = 8,
+		.lock = dio48e_regmap_lock,
+		.unlock = dio48e_regmap_unlock,
+		.lock_arg = dio48egpio,
+		.io_port = true,
+		.wr_table = &dio48e_wr_table,
+		.rd_table = &dio48e_rd_table,
+		.volatile_table = &dio48e_volatile_table,
+		.precious_table = &dio48e_precious_table,
+		.cache_type = REGCACHE_FLAT,
+	};
+
 	map = devm_regmap_init_mmio(dev, regs, &dio48e_regmap_config);
 	if (IS_ERR(map))
 		return dev_err_probe(dev, PTR_ERR(map),
 				     "Unable to initialize register map\n");
 
-	dio48egpio = devm_kzalloc(dev, sizeof(*dio48egpio), GFP_KERNEL);
-	if (!dio48egpio)
-		return -ENOMEM;
-
 	dio48egpio->map = map;
 
+	pit_regmap_config = (struct regmap_config) {
+		.name = "i8254",
+		.reg_bits = 8,
+		.reg_stride = 1,
+		.val_bits = 8,
+		.lock = pit_regmap_lock,
+		.unlock = pit_regmap_unlock,
+		.lock_arg = dio48egpio,
+		.io_port = true,
+		.wr_table = &pit_wr_table,
+		.rd_table = &pit_rd_table,
+	};
+
+	pit_config.map = devm_regmap_init_mmio(dev, regs, &pit_regmap_config);
+	if (IS_ERR(pit_config.map))
+		return dev_err_probe(dev, PTR_ERR(pit_config.map),
+				     "Unable to initialize i8254 register map\n");
+
 	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 	if (!chip)
 		return -ENOMEM;
@@ -229,6 +317,12 @@  static int dio48e_probe(struct device *dev, unsigned int id)
 	if (err)
 		return dev_err_probe(dev, err, "IRQ registration failed\n");
 
+	pit_config.parent = dev;
+
+	err = devm_i8254_regmap_register(dev, &pit_config);
+	if (err)
+		return err;
+
 	config.parent = dev;
 	config.map = map;
 	config.num_ppi = DIO48E_NUM_PPI;
@@ -249,3 +343,4 @@  module_isa_driver_with_irq(dio48e_driver, num_dio48e, num_irq);
 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 MODULE_DESCRIPTION("ACCES 104-DIO-48E GPIO driver");
 MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS(I8254);