diff mbox

[1/3] regmap: Add OneWire (W1) bus support

Message ID 20170528071120.6604-2-minimumlaw@rambler.ru (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

minimumlaw@rambler.ru May 28, 2017, 7:11 a.m. UTC 
Add basic support regmap (register map access) API for OneWire (W1) bus

Signed-off-by: Alex A. Mihaylov <minimumlaw@rambler.ru>
---
 drivers/base/regmap/Kconfig     |   6 +-
 drivers/base/regmap/Makefile    |   1 +
 drivers/base/regmap/regmap-w1.c | 241 ++++++++++++++++++++++++++++++++++++++++
 include/linux/regmap.h          |  34 ++++++
 4 files changed, 281 insertions(+), 1 deletion(-)
 create mode 100644 drivers/base/regmap/regmap-w1.c

Comments

Mark Brown May 29, 2017, 1:13 p.m. UTC | #1 
On Sun, May 28, 2017 at 10:11:18AM +0300, Alex A. Mihaylov wrote:

> +	int ret = -ENODEV;
> +
> +	mutex_lock(&sl->master->bus_mutex);
> +	if (!w1_reset_select_slave(sl)) {
> +		w1_write_8(sl->master, W1_CMD_READ_DATA);
> +		w1_write_8(sl->master, reg);
> +		*val = w1_read_8(sl->master);
> +		ret = 0;
> +	}

I asked you to move the error handling into the else case in these :(
Geert Uytterhoeven May 29, 2017, 3:07 p.m. UTC | #2 
On Sun, May 28, 2017 at 9:11 AM, Alex A. Mihaylov <minimumlaw@rambler.ru> wrote:
> Add basic support regmap (register map access) API for OneWire (W1) bus

It's called "1-wire" or "1-Wire" almost everywhere else in the kernel,
and on the Maxim
website (except in the URL
https://www.maximintegrated.com/en/products/digital/one-wire.html ;-)

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
minimumlaw@rambler.ru May 29, 2017, 4:37 p.m. UTC | #3 
29.05.17 16:13, Mark Brown пишет:

>> +	int ret = -ENODEV;
>> +
>> +	mutex_lock(&sl->master->bus_mutex);
>> +	if (!w1_reset_select_slave(sl)) {
>> +		w1_write_8(sl->master, W1_CMD_READ_DATA);
>> +		w1_write_8(sl->master, reg);
>> +		*val = w1_read_8(sl->master);
>> +		ret = 0;
>> +	}
> I asked you to move the error handling into the else case in these :(
Why do you want to see exactly the construction of if/else?

I already wrote that for me this will worsen the quality and 
understanding of the code. And another point - in fact it is not an 
error handler. This is a completely normal and permissible situation. 
There is no "disconnect" event for this bus, and consequently at any 
arbitrary time the kernel can not be sure that the device is still 
available.

My ret = -ENODEV is exactly about this.

I can see this pattern in other kernel place, like:
drivers/usb/musb/da8xx.c line 374
drivers/usb/musb/davinci.c line 381
drivers/usb/host/xhci-mtk.c line 531
and many other palces.
Mark Brown May 30, 2017, 11:50 a.m. UTC | #4 
On Mon, May 29, 2017 at 07:37:58PM +0300, Alex A. Mihaylov wrote:
> 29.05.17 16:13, Mark Brown пишет:

> > I asked you to move the error handling into the else case in these :(

> Why do you want to see exactly the construction of if/else?

I want to see some error handling in the lock so it doesn't look like
it's missing, especially since this is the unusual pattern of "mark it
as OK in an if statement then carry on running".  The code pattern is
too unusual and there's too much code and blank space between the ret =
0 meaning it takes too much effort to slow down and check that there's
not a bug.

> I already wrote that for me this will worsen the quality and understanding
> of the code. And another point - in fact it is not an error handler. This is
> a completely normal and permissible situation. There is no "disconnect"

It's an error.  It may be an expected and recoverable error but as far
as this write is concerned it's an error.

> I can see this pattern in other kernel place, like:
> drivers/usb/musb/da8xx.c line 374

This one for example looks like normal code - it's jumping to error in
the error handling cases, the success case is a normal direct return
with the error cases in the if checks and there's multiple conditions
that could trigger an error.  You need to get out of the locked region
so you have limited options but only have one conditional, moving the
assignment inside the else seems like the clearest.
diff mbox

Patch

diff --git a/drivers/base/regmap/Kconfig b/drivers/base/regmap/Kconfig
index db9d00c..413af5f 100644
--- a/drivers/base/regmap/Kconfig
+++ b/drivers/base/regmap/Kconfig
@@ -3,7 +3,7 @@ 
 # subsystems should select the appropriate symbols.
 
 config REGMAP
-	default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ)
+	default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_W1 || REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ)
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
 	select IRQ_DOMAIN if REGMAP_IRQ
@@ -24,6 +24,10 @@  config REGMAP_SPMI
 	tristate
 	depends on SPMI
 
+config REGMAP_W1
+	tristate
+	depends on W1
+
 config REGMAP_MMIO
 	tristate
 
diff --git a/drivers/base/regmap/Makefile b/drivers/base/regmap/Makefile
index 609e4c8..17741ae 100644
--- a/drivers/base/regmap/Makefile
+++ b/drivers/base/regmap/Makefile
@@ -10,3 +10,4 @@  obj-$(CONFIG_REGMAP_SPI) += regmap-spi.o
 obj-$(CONFIG_REGMAP_SPMI) += regmap-spmi.o
 obj-$(CONFIG_REGMAP_MMIO) += regmap-mmio.o
 obj-$(CONFIG_REGMAP_IRQ) += regmap-irq.o
+obj-$(CONFIG_REGMAP_W1) += regmap-w1.o
diff --git a/drivers/base/regmap/regmap-w1.c b/drivers/base/regmap/regmap-w1.c
new file mode 100644
index 0000000..6852889
--- /dev/null
+++ b/drivers/base/regmap/regmap-w1.c
@@ -0,0 +1,241 @@ 
+/*
+ * Register map access API - W1 (OneWire) support
+ *
+ * Copyright (C) 2017 OAO Radioavionica
+ * Author: Alex A. Mihaylov <minimumlaw@rambler.ru>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation
+ */
+
+#include <linux/regmap.h>
+#include <linux/module.h>
+#include "../../w1/w1.h"
+
+#include "internal.h"
+
+#define W1_CMD_READ_DATA	0x69
+#define W1_CMD_WRITE_DATA	0x6C
+
+/*
+ * OneWire slaves registers with addess 8 bit and data 8 bit
+ */
+
+static int w1_reg_a8_v8_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct device *dev = context;
+	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
+	int ret = -ENODEV;
+
+
+	if (reg > 255)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+	if (!w1_reset_select_slave(sl)) {
+		w1_write_8(sl->master, W1_CMD_READ_DATA);
+		w1_write_8(sl->master, reg);
+		*val = w1_read_8(sl->master);
+		ret = 0;
+	}
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+static int w1_reg_a8_v8_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct device *dev = context;
+	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
+	int ret = -ENODEV;
+
+
+	if (reg > 255)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+	if (!w1_reset_select_slave(sl)) {
+		w1_write_8(sl->master, W1_CMD_WRITE_DATA);
+		w1_write_8(sl->master, reg);
+		w1_write_8(sl->master, val);
+		ret = 0;
+	}
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+/*
+ * OneWire slaves registers with addess 8 bit and data 16 bit
+ */
+
+static int w1_reg_a8_v16_read(void *context, unsigned int reg,
+				unsigned int *val)
+{
+	struct device *dev = context;
+	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
+	int ret = -ENODEV;
+
+
+	if (reg > 255)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+	if (!w1_reset_select_slave(sl)) {
+		w1_write_8(sl->master, W1_CMD_READ_DATA);
+		w1_write_8(sl->master, reg);
+		*val = w1_read_8(sl->master);
+		*val |= w1_read_8(sl->master)<<8;
+		ret = 0;
+	}
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+static int w1_reg_a8_v16_write(void *context, unsigned int reg,
+				unsigned int val)
+{
+	struct device *dev = context;
+	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
+	int ret = -ENODEV;
+
+
+	if (reg > 255)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+	if (!w1_reset_select_slave(sl)) {
+		w1_write_8(sl->master, W1_CMD_WRITE_DATA);
+		w1_write_8(sl->master, reg);
+		w1_write_8(sl->master, val & 0x00FF);
+		w1_write_8(sl->master, val>>8 & 0x00FF);
+		ret = 0;
+	}
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+/*
+ * OneWire slaves registers with addess 16 bit and data 16 bit
+ */
+
+static int w1_reg_a16_v16_read(void *context, unsigned int reg,
+				unsigned int *val)
+{
+	struct device *dev = context;
+	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
+	int ret = -ENODEV;
+
+
+	if (reg > 65535)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+	if (!w1_reset_select_slave(sl)) {
+		w1_write_8(sl->master, W1_CMD_READ_DATA);
+		w1_write_8(sl->master, reg & 0x00FF);
+		w1_write_8(sl->master, reg>>8 & 0x00FF);
+		*val = w1_read_8(sl->master);
+		*val |= w1_read_8(sl->master)<<8;
+		ret = 0;
+	}
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+static int w1_reg_a16_v16_write(void *context, unsigned int reg,
+				unsigned int val)
+{
+	struct device *dev = context;
+	struct w1_slave *sl = container_of(dev, struct w1_slave, dev);
+	int ret = -ENODEV;
+
+
+	if (reg > 65535)
+		return -EINVAL;
+
+	mutex_lock(&sl->master->bus_mutex);
+	if (!w1_reset_select_slave(sl)) {
+		w1_write_8(sl->master, W1_CMD_WRITE_DATA);
+		w1_write_8(sl->master, reg & 0x00FF);
+		w1_write_8(sl->master, reg>>8 & 0x00FF);
+		w1_write_8(sl->master, val & 0x00FF);
+		w1_write_8(sl->master, val>>8 & 0x00FF);
+		ret = 0;
+	}
+	mutex_unlock(&sl->master->bus_mutex);
+
+	return ret;
+}
+
+static struct regmap_bus regmap_w1_bus_a8_v8 = {
+	.reg_read = w1_reg_a8_v8_read,
+	.reg_write = w1_reg_a8_v8_write,
+};
+
+static struct regmap_bus regmap_w1_bus_a8_v16 = {
+	.reg_read = w1_reg_a8_v16_read,
+	.reg_write = w1_reg_a8_v16_write,
+};
+
+static struct regmap_bus regmap_w1_bus_a16_v16 = {
+	.reg_read = w1_reg_a16_v16_read,
+	.reg_write = w1_reg_a16_v16_write,
+};
+
+static const struct regmap_bus *regmap_get_w1_bus(struct device *w1_dev,
+					const struct regmap_config *config)
+{
+	if (config->reg_bits == 8 && config->val_bits == 8)
+		return &regmap_w1_bus_a8_v8;
+
+	if (config->reg_bits == 8 && config->val_bits == 16)
+		return &regmap_w1_bus_a8_v16;
+
+	if (config->reg_bits == 16 && config->val_bits == 16)
+		return &regmap_w1_bus_a16_v16;
+
+	return ERR_PTR(-ENOTSUPP);
+}
+
+struct regmap *__regmap_init_w1(struct device *w1_dev,
+				 const struct regmap_config *config,
+				 struct lock_class_key *lock_key,
+				 const char *lock_name)
+{
+
+	const struct regmap_bus *bus = regmap_get_w1_bus(w1_dev, config);
+
+	if (IS_ERR(bus))
+		return ERR_CAST(bus);
+
+	return __regmap_init(w1_dev, bus, w1_dev, config,
+			 lock_key, lock_name);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__regmap_init_w1);
+
+struct regmap *__devm_regmap_init_w1(struct device *w1_dev,
+				 const struct regmap_config *config,
+				 struct lock_class_key *lock_key,
+				 const char *lock_name)
+{
+
+	const struct regmap_bus *bus = regmap_get_w1_bus(w1_dev, config);
+
+	if (IS_ERR(bus))
+		return ERR_CAST(bus);
+
+	return __devm_regmap_init(w1_dev, bus, w1_dev, config,
+				 lock_key, lock_name);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__devm_regmap_init_w1);
+
+MODULE_LICENSE("GPL");
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index e886492..86eeacc 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -461,6 +461,10 @@  struct regmap *__regmap_init_spmi_ext(struct spmi_device *dev,
 				      const struct regmap_config *config,
 				      struct lock_class_key *lock_key,
 				      const char *lock_name);
+struct regmap *__regmap_init_w1(struct device *w1_dev,
+				 const struct regmap_config *config,
+				 struct lock_class_key *lock_key,
+				 const char *lock_name);
 struct regmap *__regmap_init_mmio_clk(struct device *dev, const char *clk_id,
 				      void __iomem *regs,
 				      const struct regmap_config *config,
@@ -493,6 +497,10 @@  struct regmap *__devm_regmap_init_spmi_ext(struct spmi_device *dev,
 					   const struct regmap_config *config,
 					   struct lock_class_key *lock_key,
 					   const char *lock_name);
+struct regmap *__devm_regmap_init_w1(struct device *w1_dev,
+				      const struct regmap_config *config,
+				      struct lock_class_key *lock_key,
+				      const char *lock_name);
 struct regmap *__devm_regmap_init_mmio_clk(struct device *dev,
 					   const char *clk_id,
 					   void __iomem *regs,
@@ -597,6 +605,19 @@  int regmap_attach_dev(struct device *dev, struct regmap *map,
 				dev, config)
 
 /**
+ * regmap_init_w1() - Initialise register map
+ *
+ * @w1_dev: Device that will be interacted with
+ * @config: Configuration for register map
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer to
+ * a struct regmap.
+ */
+#define regmap_init_w1(w1_dev, config)					\
+	__regmap_lockdep_wrapper(__regmap_init_w1, #config,		\
+				w1_dev, config)
+
+/**
  * regmap_init_mmio_clk() - Initialise register map with register clock
  *
  * @dev: Device that will be interacted with
@@ -712,6 +733,19 @@  bool regmap_ac97_default_volatile(struct device *dev, unsigned int reg);
 				dev, config)
 
 /**
+ * devm_regmap_init_w1() - Initialise managed register map
+ *
+ * @w1_dev: Device that will be interacted with
+ * @config: Configuration for register map
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer
+ * to a struct regmap.  The regmap will be automatically freed by the
+ * device management code.
+ */
+#define devm_regmap_init_w1(w1_dev, config)				\
+	__regmap_lockdep_wrapper(__devm_regmap_init_w1, #config,	\
+				w1_dev, config)
+/**
  * devm_regmap_init_mmio_clk() - Initialise managed register map with clock
  *
  * @dev: Device that will be interacted with