[RFC PATCH 0/5] regmap: Add Parity bit Calculation to regmaps

[RFC PATCH 0/5] regmap: Add Parity bit Calculation to regmaps

[linuxkernel]

From: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>

this patch set adds parity bit calculation to regmaps

this allow support for devices that require parity bits in their
communications.

e.g. the texas instruments TPS92518-Q1 which requires a parity bit in the
7th bit of a 16 bit spi frame 
or the TPS92518-Q1 which requires a parity bit in the 1st bit of a 16 bit 
spi frame

parity aimed to work devices where parity in reg block
e.g. TPS65311-Q1 and TPS92518-Q1

TPS65311-Q1 frame format	[PWRRRRRRDDDDDDDD]
TPS92518-Q1	frame format	[WRRRRRPDDDDDDDDD]
P - parity bit, W - Read/Write bit, R - register, D -register data

TPS65311-Q1 parity mask 0x8000 (1000000000000000)
TPS92518-Q1	parity mask	0x0200 (0000001000000000)


calculates parity bit based up parity function defined by
regmap_config->parity_calc

regmap_config->parity_calc defaults to regmap_parity_calc_even()

adds alternate parity function regmap_parity_calc_odd()

calculates parity bit for writes if regmap_config->parity_write_mask is > 0
calculates parity bit for reads if regmap_config->parity_read_mask is > 0

parity is not calculated when bus implements reg_update_bits()


Altered the regmap_format_X_X_write functions to account for padding bits
allowing masks to write to either end of register address for formatted 
writes

Altered formatted_write to apply write and parity masks

Added parsers for 9 bit data format which are written by formatted write

Christopher Tyerman (5):
  Add Parity bit Calculation to regmaps
  Altered regmap_X_X_write functions to account for padding bits
  Added setting of writemap to formatted write
  Add Parity Calculation to formatted write
  Add parser for X_9 formats

 drivers/base/regmap/internal.h |   6 +
 drivers/base/regmap/regmap.c   | 250 +++++++++++++++++++++++++++++++--
 include/linux/regmap.h         |  32 +++++
 3 files changed, 280 insertions(+), 8 deletions(-)


base-commit: 02d6fdecb9c38de19065f6bed8d5214556fd061d
-- 
2.25.1

[RFC PATCH 1/5] regmap: Add Parity bit Calculation to regmaps

[linuxkernel]

From: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>

regmap.h

Added parity_read_mask to regmap_config
Added parity_write_mask to regmap_config
Added (*parity_calc)() to regmap_config

Added regmap_parity_calc_even() Added regmap_parity_calc_odd()

internal.h

Added parity_read_mask to regmap
Added parity_write_mask to regmap
Added (*parity_calc) to regmap

regmap.c
Altered _regmap_raw_write_impl() to calculate parity
Altered _regmap_raw_read() to calculate parity
Added regmap_set_work_buf_parity_mask()
Added regmap_parity_calc_even()
Added regmap_parity_calc_odd()
Added parity_even()
Added parity16_even(u16 v)
Added parity32_even(u32 v)
Added parity64_even(u64 v)

Signed-off-by: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>
---
 drivers/base/regmap/internal.h |   6 ++
 drivers/base/regmap/regmap.c   | 168 ++++++++++++++++++++++++++++++++-
 include/linux/regmap.h         |  32 +++++++
 3 files changed, 204 insertions(+), 2 deletions(-)

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index b1905916f7af..78df50694cf4 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -168,6 +168,12 @@ struct regmap {
 
 	/* if set, the regmap core can sleep */
 	bool can_sleep;
+
+	unsigned long parity_write_mask;
+	unsigned long parity_read_mask;
+
+	bool (*parity_calc)(unsigned long rwmask, unsigned int reg,
+						const void *val, size_t val_len);
 };
 
 struct regcache_ops {
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 2d74f9f82aa9..05c104659381 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -57,6 +57,13 @@ static int _regmap_bus_reg_write(void *context, unsigned int reg,
 static int _regmap_bus_raw_write(void *context, unsigned int reg,
 				 unsigned int val);
 
+static bool parity_even(uint v);
+
+static bool parity8_even(u8 v);
+static bool parity16_even(u16 v);
+static bool parity32_even(u32 v);
+static bool parity64_even(u64 v);
+
 bool regmap_reg_in_ranges(unsigned int reg,
 			  const struct regmap_range *ranges,
 			  unsigned int nranges)
@@ -892,6 +899,14 @@ struct regmap *__regmap_init(struct device *dev,
 		map->reg_update_bits = bus->reg_update_bits;
 	}
 
+	map->parity_write_mask = config->parity_write_mask;
+	map->parity_read_mask = config->parity_read_mask;
+
+	if (config->parity_calc)
+		map->parity_calc = config->parity_calc;
+	else
+		map->parity_calc = regmap_parity_calc_even;
+
 	reg_endian = regmap_get_reg_endian(bus, config);
 	val_endian = regmap_get_val_endian(dev, bus, config);
 
@@ -1655,6 +1670,31 @@ static void regmap_set_work_buf_flag_mask(struct regmap *map, int max_bytes,
 		buf[i] |= (mask >> (8 * i)) & 0xff;
 }
 
+static void regmap_set_work_buf_parity_mask(struct regmap *map, int max_bytes,
+					  unsigned long mask, unsigned long rwmask,
+					  unsigned int reg, const void *val, size_t val_len)
+{
+
+	bool paritybit;
+	u8 *buf;
+	int i;
+
+	if (!mask || !map->work_buf)
+		return;
+
+	paritybit = map->parity_calc(rwmask, reg, val, val_len);
+
+
+	if (paritybit) {
+		buf = map->work_buf;
+
+		for (i = 0; i < max_bytes; i++)
+			buf[i] |= (mask >> (8 * i)) & 0xff;
+	}
+}
+
+
+
 static int _regmap_raw_write_impl(struct regmap *map, unsigned int reg,
 				  const void *val, size_t val_len, bool noinc)
 {
@@ -1736,7 +1776,12 @@ static int _regmap_raw_write_impl(struct regmap *map, unsigned int reg,
 
 	map->format.format_reg(map->work_buf, reg, map->reg_shift);
 	regmap_set_work_buf_flag_mask(map, map->format.reg_bytes,
-				      map->write_flag_mask);
+								  map->write_flag_mask);
+
+
+	regmap_set_work_buf_parity_mask(map, map->format.reg_bytes,
+				map->parity_write_mask, map->write_flag_mask, reg, val, val_len);
+
 
 	/*
 	 * Essentially all I/O mechanisms will be faster with a single
@@ -1748,6 +1793,9 @@ static int _regmap_raw_write_impl(struct regmap *map, unsigned int reg,
 		val = work_val;
 	}
 
+
+
+
 	if (map->async && map->bus->async_write) {
 		struct regmap_async *async;
 
@@ -2674,7 +2722,12 @@ static int _regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
 
 	map->format.format_reg(map->work_buf, reg, map->reg_shift);
 	regmap_set_work_buf_flag_mask(map, map->format.reg_bytes,
-				      map->read_flag_mask);
+						map->read_flag_mask);
+
+	regmap_set_work_buf_parity_mask(map, map->format.reg_bytes,
+						map->parity_read_mask, map->read_flag_mask, reg,
+						val, val_len);
+
 	trace_regmap_hw_read_start(map, reg, val_len / map->format.val_bytes);
 
 	ret = map->bus->read(map->bus_context, map->work_buf,
@@ -3340,3 +3393,114 @@ static int __init regmap_initcall(void)
 	return 0;
 }
 postcore_initcall(regmap_initcall);
+
+
+/**
+ * regmap_parity_calc_even() - calculates Value of parity bit for even parity
+ *
+ * @rwmask: value of the read/write mask
+ * @reg: value of register
+ * @val: pointer to value of data
+ * @val_len: size of val
+ *
+ * Calculate the value of the parity bit for even parity
+ */
+bool regmap_parity_calc_even(unsigned long rwmask, unsigned int reg,
+							 const void *val, size_t val_len)
+{
+	bool paritybuf = 0;
+	uint count = 0;
+
+	while (count < val_len) {
+		if (val_len - count >= 8) {
+			paritybuf ^= parity64_even(*(u64 *)val+count);
+			count += 8;
+		} else if (val_len - count >= 4) {
+			paritybuf ^= parity32_even(*(u32 *)val+count);
+			count += 4;
+		} else if (val_len - count >= 2) {
+			paritybuf ^= parity16_even(*(u16 *)val+count);
+			count += 2;
+		} else if (val_len - count >= 1) {
+			paritybuf ^= parity8_even(*(u8 *)val+count);
+			count += 1;
+		}
+	}
+
+	return (parity_even(rwmask) ^ parity_even(reg) ^ paritybuf);
+}
+EXPORT_SYMBOL_GPL(regmap_parity_calc_even);
+
+/**
+ * regmap_parity_calc_odd() - calculates Value of parity bit for odd parity
+ *
+ * @rwmask: value of the read/write mask
+ * @reg: value of register
+ * @val: pointer to value of data
+ * @val_len: size of val
+ *
+ * Calculate the value of the parity bit for odd parity
+ */
+
+bool regmap_parity_calc_odd(unsigned long rwmask, unsigned int reg,
+							const void *val, size_t val_len)
+{
+	return !(regmap_parity_calc_even(rwmask, reg, val, val_len));
+
+
+}
+EXPORT_SYMBOL_GPL(regmap_parity_calc_odd);
+
+static bool parity_even(uint v)
+{
+	switch (sizeof(v)) {
+	case 1:
+		return parity8_even((u8)v);
+	case 2:
+		return parity16_even((u16)v);
+	case 4:
+		return parity32_even((u32)v);
+	case 8:
+	default:
+		return parity64_even((u64)v);
+
+	}
+}
+static bool parity8_even(u8 v)
+{
+	v ^= v >> 4;
+	v ^= v >> 2;
+	v ^= v >> 1;
+	return v & 1;
+}
+
+
+static bool parity16_even(u16 v)
+{
+	v ^= v >> 8;
+	v ^= v >> 4;
+	v ^= v >> 2;
+	v ^= v >> 1;
+	return v & 1;
+}
+
+static bool parity32_even(u32 v)
+{
+	v ^= v >> 16;
+	v ^= v >> 8;
+	v ^= v >> 4;
+	v ^= v >> 2;
+	v ^= v >> 1;
+	return v & 1;
+}
+
+static bool parity64_even(u64 v)
+{
+	v ^= v >> 32;
+	v ^= v >> 16;
+	v ^= v >> 8;
+	v ^= v >> 4;
+	v ^= v >> 2;
+	v ^= v >> 1;
+	return v & 1;
+}
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 22652e5fbc38..511fc9228e1d 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -354,6 +354,10 @@ typedef void (*regmap_unlock)(void *);
  * @hwlock_mode: The hardware spinlock mode, should be HWLOCK_IRQSTATE,
  *		 HWLOCK_IRQ or 0.
  * @can_sleep: Optional, specifies whether regmap operations can sleep.
+ *
+ * @parity_read_mask: bit mask of location of parity bit for reads
+ * @parity_write_mask: bit mask of location of parity bit for writes
+ * @parity_calc: Optional callback to calculate parity, defaults to even parity
  */
 struct regmap_config {
 	const char *name;
@@ -416,6 +420,12 @@ struct regmap_config {
 	unsigned int hwlock_mode;
 
 	bool can_sleep;
+
+	unsigned long parity_read_mask;
+	unsigned long parity_write_mask;
+	bool (*parity_calc)(unsigned long rwmask, unsigned int reg,
+						const void *val, size_t val_len);
+
 };
 
 /**
@@ -1237,6 +1247,11 @@ static inline int regmap_clear_bits(struct regmap *map,
 
 int regmap_test_bits(struct regmap *map, unsigned int reg, unsigned int bits);
 
+bool regmap_parity_calc_even(unsigned long rwmask, unsigned int reg,
+								const void *val, size_t val_len);
+bool regmap_parity_calc_odd(unsigned long rwmask, unsigned int reg,
+								const void *val, size_t val_len);
+
 /**
  * struct reg_field - Description of an register field
  *
@@ -1866,6 +1881,23 @@ static inline struct device *regmap_get_device(struct regmap *map)
 	return NULL;
 }
 
+static inline bool regmap_parity_calc_even(unsigned long rwmask, unsigned int reg,
+						const void *val, size_t val_len)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return NULL;
+}
+
+static inline bool regmap_parity_calc_odd(unsigned long rwmask, unsigned int reg,
+						const void *val, size_t val_len)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return NULL;
+}
+
+
 #endif
 
+
+
 #endif
-- 
2.25.1

[RFC PATCH 2/5] regmap: Altered regmap_X_X_write functions to account for padding bits

[linuxkernel]

From: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>

	modified:   drivers/base/regmap/regmap.c

Signed-off-by: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>
---
 drivers/base/regmap/regmap.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 05c104659381..07d6d804c4b9 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -232,42 +232,52 @@ static void regmap_format_2_6_write(struct regmap *map,
 				     unsigned int reg, unsigned int val)
 {
 	u8 *out = map->work_buf;
+	u8 shift = map->reg_shift;
 
-	*out = (reg << 6) | val;
+	*out = (reg << (6 + shift) | val);
 }
 
 static void regmap_format_4_12_write(struct regmap *map,
 				     unsigned int reg, unsigned int val)
 {
+	u8 shift = map->reg_shift;
 	__be16 *out = map->work_buf;
-	*out = cpu_to_be16((reg << 12) | val);
+
+	*out = cpu_to_be16((reg << (12 + shift)) | val);
 }
 
 static void regmap_format_7_9_write(struct regmap *map,
 				    unsigned int reg, unsigned int val)
 {
+	u8 shift = map->reg_shift;
 	__be16 *out = map->work_buf;
-	*out = cpu_to_be16((reg << 9) | val);
+
+	*out = cpu_to_be16((reg << (9 + shift)) | val);
 }
 
 static void regmap_format_7_17_write(struct regmap *map,
 				    unsigned int reg, unsigned int val)
 {
+	u8 shift = map->reg_shift;
 	u8 *out = map->work_buf;
 
 	out[2] = val;
 	out[1] = val >> 8;
-	out[0] = (val >> 16) | (reg << 1);
+	out[0] = (val >> 16) | (reg << (1 + shift));
 }
 
 static void regmap_format_10_14_write(struct regmap *map,
 				    unsigned int reg, unsigned int val)
 {
+	u8 shift = map->reg_shift;
 	u8 *out = map->work_buf;
 
 	out[2] = val;
-	out[1] = (val >> 8) | (reg << 6);
-	out[0] = reg >> 2;
+	out[1] = (val >> 8) | (reg << (6 + shift));
+	if (shift <= 2)
+		out[0] = reg >> (2 - shift);
+	else
+		out[0] = reg << shift;
 }
 
 static void regmap_format_8(void *buf, unsigned int val, unsigned int shift)
-- 
2.25.1

[RFC PATCH 3/5] regmap: Added setting of writemap to formatted write

[linuxkernel]

From: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>

Added regmap_set_work_buf_flag_mask to _regmap_bus_formatted_write
to ensure correct write bit value set when writemask defined

	modified:   drivers/base/regmap/regmap.c

Signed-off-by: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>
---
 drivers/base/regmap/regmap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 07d6d804c4b9..ec91eff52465 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1964,6 +1964,9 @@ static int _regmap_bus_formatted_write(void *context, unsigned int reg,
 
 	map->format.format_write(map, reg, val);
 
+	regmap_set_work_buf_flag_mask(map, map->format.reg_bytes,
+					      map->write_flag_mask);
+
 	trace_regmap_hw_write_start(map, reg, 1);
 
 	ret = map->bus->write(map->bus_context, map->work_buf,
-- 
2.25.1

[RFC PATCH 4/5] regmap: Add Parity Calculation to formatted write

[linuxkernel]

From: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>

Altered formated write to set parity bit according to parity_write_mask

	modified:   drivers/base/regmap/regmap.c

Signed-off-by: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>
---
 drivers/base/regmap/regmap.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index ec91eff52465..ea1664fa4c60 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1967,6 +1967,10 @@ static int _regmap_bus_formatted_write(void *context, unsigned int reg,
 	regmap_set_work_buf_flag_mask(map, map->format.reg_bytes,
 					      map->write_flag_mask);
 
+	regmap_set_work_buf_parity_mask(map, map->format.reg_bytes,
+						map->parity_write_mask, map->write_flag_mask, reg,
+						&val, sizeof(val));
+
 	trace_regmap_hw_write_start(map, reg, 1);
 
 	ret = map->bus->write(map->bus_context, map->work_buf,
-- 
2.25.1

[RFC PATCH 5/5] regmap: Add parser for X_9 formats

[linuxkernel]

From: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>

added 9 bit Parser functions

these operate in same way as 16 bit parsers but mask out higher bits

regmap_parse_9_be()
regmap_parse_9_be_inplace()
regmap_parse_9_le()
regmap_parse_9_le_inplace()
regmap_parse_9_native()

	modified:   drivers/base/regmap/regmap.c

Signed-off-by: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>
---
 drivers/base/regmap/regmap.c | 53 ++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index ea1664fa4c60..3f105e4266b4 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -365,6 +365,39 @@ static unsigned int regmap_parse_8(const void *buf)
 	return b[0];
 }
 
+static unsigned int regmap_parse_9_be(const void *buf)
+{
+	return get_unaligned_be16(buf) & 0x1FF;
+}
+
+static unsigned int regmap_parse_9_le(const void *buf)
+{
+
+	return get_unaligned_le16(buf) & 0x1FF;
+}
+
+static void regmap_parse_9_be_inplace(void *buf)
+{
+	u16 v = get_unaligned_be16(buf) & 0x1FF;
+
+	memcpy(buf, &v, sizeof(v));
+}
+
+static void regmap_parse_9_le_inplace(void *buf)
+{
+	u16 v = get_unaligned_le16(buf) & 0x1FF;
+
+	memcpy(buf, &v, sizeof(v));
+}
+
+static unsigned int regmap_parse_9_native(const void *buf)
+{
+	u16 v;
+
+	memcpy(&v, buf, sizeof(v));
+	return v & 0x1FF;
+}
+
 static unsigned int regmap_parse_16_be(const void *buf)
 {
 	return get_unaligned_be16(buf);
@@ -1047,6 +1080,26 @@ struct regmap *__regmap_init(struct device *dev,
 		map->format.parse_val = regmap_parse_8;
 		map->format.parse_inplace = regmap_parse_inplace_noop;
 		break;
+	case 9:
+		switch (val_endian) {
+		case REGMAP_ENDIAN_BIG:
+			//map->format.format_val = regmap_format_9_be;
+			map->format.parse_val = regmap_parse_9_be;
+			map->format.parse_inplace = regmap_parse_9_be_inplace;
+			break;
+		case REGMAP_ENDIAN_LITTLE:
+			//map->format.format_val = regmap_format_9_le;
+			map->format.parse_val = regmap_parse_9_le;
+			map->format.parse_inplace = regmap_parse_9_le_inplace;
+			break;
+		case REGMAP_ENDIAN_NATIVE:
+			//map->format.format_val = regmap_format_9_native;
+			map->format.parse_val = regmap_parse_9_native;
+			break;
+		default:
+			goto err_hwlock;
+		}
+		break;
 	case 16:
 		switch (val_endian) {
 		case REGMAP_ENDIAN_BIG:
-- 
2.25.1

Re: [RFC PATCH 1/5] regmap: Add Parity bit Calculation to regmaps

[Mark Brown]

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On Fri, Dec 17, 2021 at 10:41:00PM +0000, linuxkernel@fbautosys.co.uk wrote:
> From: Christopher Tyerman <c.tyerman@firebladeautomationsystems.co.uk>
> 
> regmap.h
> 
> Added parity_read_mask to regmap_config
> Added parity_write_mask to regmap_config
> Added (*parity_calc)() to regmap_config
> 
> Added regmap_parity_calc_even() Added regmap_parity_calc_odd()
> 
> internal.h
> 
> Added parity_read_mask to regmap
> Added parity_write_mask to regmap
> Added (*parity_calc) to regmap
> 
> regmap.c
> Altered _regmap_raw_write_impl() to calculate parity
> Altered _regmap_raw_read() to calculate parity
> Added regmap_set_work_buf_parity_mask()
> Added regmap_parity_calc_even()
> Added regmap_parity_calc_odd()
> Added parity_even()
> Added parity16_even(u16 v)
> Added parity32_even(u32 v)
> Added parity64_even(u64 v)

This isn't a good changelog, the changelog needs to describe what is
being changed in the code and why in a way that provides information to
the human reader.  Instead this is essentially a list of code level
changes in the diff.  There's some advice on changelogs in
submitting-patches.rst.  Without a clear changelog it's hard to review
things as it's not clear what the goals are.

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