i2c: add master driver for mellanox systems

From: Vadim Pasternak <[email protected]>

Device driver for Mellanox I2C controller logic, implemented in Lattice CPLD device.
Device supports:
- Master mode
- One physical bus
- Polling mode

The Kconfig currently controlling compilation of this code is:
drivers/i2c/busses/Kconfig:config I2C_MLXCPLD

---
v8->v9
Comments pointed out by Wolfram:
- fix typo in comment;
- use quirk parameters for the message number validation;
v7->v8
Comments pointed out by Wolfram:
- Remove descriptions for two structures, since the members have self-explaining names;
- Populate the structure i2c_adapter_quirks, so core will make length validation, as a result remove mlxcpld_i2c_invalid_len,
and move common length calculation to mlxcpld_i2c_xfer. Consider removing of mlxcpld_i2c_check_msg_params after core quirks is able to handle messages full validation;
- Use ENXIO error code for NACK;
v6->v7
Comments pointed out by Peter:
- Fix grammar in doc file;
- Fix description for CMD in doc file;
- Fix grammar for NUM_DATA, DATAx in doc file;
- Rename mlxcpld_i2c_curr_transf to mlxcpld_i2c_curr_xfer;
- Make code in mlxcpld_i2c_lpc_write_buf more readable and mlxcpld_i2c_lpc_read_buf, compact and elegant;
- Fix multiline comments;
v5->v6:
Comments pointed out by Vladimir:
- Drop the line with module path from the header;
- In description of mlxcpld_i2c_priv remove lpc_gen_dec_reg asnd dev_id;
- In mlxcpld_i2c_priv change type of the filed base_addr to u16 for the alignment with in/out and remove unused dev_id;
- Fix misspelling in comment for mlxcpld_i2c_invalid_len;
- Remove comment regarding EBUSY return in mlxcpld_i2c_check_busy;
- Use sizeof of the target storage in allocation in probe routine;
v4->v5:
Comments pointed out by Vladimir:
- Remove "default n" from Kconfig;
- Fix the comments for timeout and pool time;
- Optimize error flow in mlxcpld_i2c_probe;
v3->v4:
Comments pointed out by Vladimir:
- Set default to no in Kconfig;
- Make mlxcpld_i2c_plat_dev static and add empty line before the declaration;
- In function mlxcpld_i2c_invalid_len remove (msg->len < 0), since len is unsigned;
- Remove unused symbol mlxcpld_i2c_plat_dev;
- Remove extra spaces in comments to mlxcpld_i2c_check_msg_params;
- Remove unnecessary round braces in mlxcpld_i2c_set_transf_data;
- Remove the assignment of 'i' variable in mlxcpld_i2c_wait_for_tc;
- Add extra line in mlxcpld_i2c_xfer;
- Move assignment of the adapter's fields retries and nr inside mlxcpld_i2c_adapter declaration;
v2->v3:
Comments pointed out by Vladimir:
- Use tab symbol as indentation in Kconfig
- Add the Kconfig section preserving the alphabetical order - added within "Other I2C/SMBus bus drivers" after I2C_ELEKTOR (but after this sections others are not follow alphabetical);
- Change license to dual;
- Replace ADRR with ADDR in macros;
- Remove unused macros: MLXCPLD_LPCI2C_LPF_DFLT, MLXCPLD_LPCI2C_HALF_CYC_100, MLXCPLD_LPCI2C_I2C_HOLD_100, MLXCPLD_LPCI2C_HALF_CYC_REG, MLXCPLD_LPCI2C_I2C_HOLD_REG;
- Fix checkpatch warnings (**/ and the end of comment);
- Add empty line before structures mlxcpld_i2c_regs, mlxcpld_i2c_curr_transf, mlxcpld_i2c_priv;
- Remove unused structure mlxcpld_i2c_regs;
- Remove from mlxcpld_i2c_priv the next fields:
retr_num, poll_time, block_sz, xfer_to; use instead macros
respectively: MLXCPLD_I2C_RETR_NUM, MLXCPLD_I2C_POLL_TIME, MLXCPLD_I2C_DATA_REG_SZ, MLXCPLD_I2C_XFER_TO;
- In mlxcpld_i2c_invalid_len remove unnecessary else;
- Optimize mlxcpld_i2c_set_transf_data;
- mlxcpld_i2c_reset - add empty lines after/before mutex lock/unlock;
- mlxcpld_i2c_wait_for_free - cover case timeout is equal MLXCPLD_I2C_XFER_TO;
- mlxcpld_i2c_wait_for_tc:
- Do not assign err in declaration (also err is removed);
- Insert empty line before case MLXCPLD_LPCI2C_ACK_IND;
- inside case MLXCPLD_LPCI2C_ACK_IND - avoid unnecessary

     indentation;

- Remove case MLXCPLD_LPCI2C_ERR_IND and remove this macro;
- Add empty lines in mlxcpld_i2c_xfer before/after mutex_lock/ mutex_unlock;
- In mlxcpld_i2c_probe add emtpy line after platform_set_drvdata;
- Replace platfrom handle pdev in mlxcpld_i2c_priv with the pointer to the structure device;
- Place assignment of base_addr near the others;
- Enclose e-mail with <>;
Fixes added by Vadim:
- Change structure description format according to Documentation/kernel-documentation.rst guideline;
- mlxcpld_i2c_wait_for_tc: return error if status reaches default case;
v1->v2
Fixes added by Vadim:
- Put new record in Makefile in alphabetic order;
- Remove http://www.mellanox.com from MAINTAINERS record;

---
 Documentation/i2c/busses/i2c-mlxcpld |  47 ++++
 MAINTAINERS                          |   8 +
 drivers/i2c/busses/Kconfig           |  11 +
 drivers/i2c/busses/Makefile          |   1 +
 drivers/i2c/busses/i2c-mlxcpld.c     | 504 +++++++++++++++++++++++++++++++++++
 5 files changed, 571 insertions(+)
 create mode 100644 Documentation/i2c/busses/i2c-mlxcpld
 create mode 100644 drivers/i2c/busses/i2c-mlxcpld.c

new file mode 100644
index 0000000..4e46c44
@@ -0,0 +1,47 @@
+Driver i2c-mlxcpld
+
+Author: Michael Shych <[email protected]>
+
+This is the Mellanox I2C controller logic, implemented in Lattice CPLD
+device.
+Device supports:
+ - Master mode.
+ - One physical bus.
+ - Polling mode.
+
+This controller is equipped within the next Mellanox systems:
+"msx6710", "msx6720", "msb7700", "msn2700", "msx1410", "msn2410", "msb7800",
+"msn2740", "msn2100".
+
+The next transaction types are supported:
+ - Receive Byte/Block.
+ - Send Byte/Block.
+ - Read Byte/Block.
+ - Write Byte/Block.
+
+Registers:
+CTRL		0x1 - control reg.
+			Resets all the registers.
+HALF_CYC	0x4 - cycle reg.
+			Configure the width of I2C SCL half clock cycle (in 4 LPC_CLK
+			units).
+I2C_HOLD	0x5 - hold reg.
+			OE (output enable) is delayed by value set to this register
+			(in LPC_CLK units)
+CMD			0x6 - command reg.
+			Bit 0, 0 = write, 1 = read.
+			Bits [7:1] - the 7bit Address of the I2C device.
+			It should be written last as it triggers an I2C transaction.
+NUM_DATA	0x7 - data size reg.
+			Number of data bytes to write in read transaction
+NUM_ADDR	0x8 - address reg.
+			Number of address bytes to write in read transaction.
+STATUS		0x9 - status reg.
+			Bit 0 - transaction is completed.
+			Bit 4 - ACK/NACK.
+DATAx		0xa - 0x54  - 68 bytes data buffer regs.
+			For write transaction address is specified in four first bytes
+			(DATA1 - DATA4), data starting from DATA4.
+			For read transactions address is sent in a separate transaction and
+			specified in the four first bytes (DATA0 - DATA3). Data is read
+			starting from DATA0.

index 411e3b8..26d05f8 100644
@@ -7881,6 +7881,14 @@ W:	http://www.mellanox.com
 Q:	http://patchwork.ozlabs.org/project/netdev/list/
 F:	drivers/net/ethernet/mellanox/mlxsw/
 
+MELLANOX MLXCPLD I2C DRIVER
+M:	Vadim Pasternak <[email protected]>
+M:	Michael Shych <[email protected]>
+L:	[email protected]
+S:	Supported
+F:	drivers/i2c/busses/i2c-mlxcpld.c
+F:	Documentation/i2c/busses/i2c-mlxcpld
+
 MELLANOX MLXCPLD LED DRIVER
 M:	Vadim Pasternak <[email protected]>
 L:	[email protected]

index d252276..6399cea 100644
@@ -1150,6 +1150,17 @@ config I2C_ELEKTOR
 	  This support is also available as a module.  If so, the module
 	  will be called i2c-elektor.
 
+config I2C_MLXCPLD
+	tristate "Mellanox I2C driver"
+	depends on X86_64
+	help
+	  This exposes the Mellanox platform I2C busses to the linux I2C layer
+	  for X86 based systems.
+	  Controller is implemented as CPLD logic.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called as i2c-mlxcpld.
+
 config I2C_PCA_ISA
 	tristate "PCA9564/PCA9665 on an ISA bus"
 	depends on ISA

index 29764cc..645bf08 100644
@@ -116,6 +116,7 @@ obj-$(CONFIG_I2C_BCM_KONA)	+= i2c-bcm-kona.o
 obj-$(CONFIG_I2C_BRCMSTB)	+= i2c-brcmstb.o
 obj-$(CONFIG_I2C_CROS_EC_TUNNEL)	+= i2c-cros-ec-tunnel.o
 obj-$(CONFIG_I2C_ELEKTOR)	+= i2c-elektor.o
+obj-$(CONFIG_I2C_MLXCPLD)	+= i2c-mlxcpld.o
 obj-$(CONFIG_I2C_OPAL)		+= i2c-opal.o
 obj-$(CONFIG_I2C_PCA_ISA)	+= i2c-pca-isa.o
 obj-$(CONFIG_I2C_SIBYTE)	+= i2c-sibyte.o

2.1.4

Applied to for-next, thanks!

Thank you very,

Vadim.