AT91: replace broken TWI driver i2c-at91.c
Subsystems (4)
v10 cover AT91: replace broken TWI driver i2c-at91.c
The old driver has two main deficencies:
i) No repeated start (Sr) condiction is possible, this makes it unusable e.g. for most SMBus transfers.
ii) I/O was done with polling/busy waiting what caused over-/underruns
even at light system loads and clock speeds.
The new driver overcomes these deficencies and in addition allows for more than one TWI interface.
A remaining limitation is the fact, that only one repeated start is possible (two concatenated messages). This limitation is imposed by the hardware. However, this should not be a problem as all common i2c-client communication does not rely on more than one repeated start.
v10: - applied fix for RXRDY overrun bug submitted by Hubert Feurstein
- applied fix for calculating twi_clk
v9: - merge i2c-at91.c patches to single patch
- rewrite cwgr reg after timeout
v8: - remove local include
- remove cpu_is_rm9200() and put twi hw bug info in platform_device
- use readl/writel_relaxed instead of __raw_readl/writel
v7: i) fix bug if internal address > 1 byte
ii) send stop when len == 1 (both reported by Carsten Behling)
v6: support for I2C_SMBUS_BLOCK_DATA transfers.
Better use of clk_(un)prepare().
More sensible transfer timeout.
v5: Another round of review comments from Ryan Mallon, Felipe Balbi
and Russell King: convert twi clk to use .dev_id, cleanups
v4: Integrated more review comments from Ryan Mallon and Felipe Balbi:
Moved register include file to local include, code cleanups
v3: Integrated review comments from Ryan Mallon and Felipe Balbi
v2: Fixed whitespace issue
Nikolaus Voss (4):
drivers/i2c/busses/i2c-at91.c: remove broken driver Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk drivers/i2c/busses/i2c-at91.c: add new driver
G45 TWI: remove open drain setting for twi function gpios
arch/arm/mach-at91/at91cap9.c | 1 + arch/arm/mach-at91/at91rm9200.c | 1 + arch/arm/mach-at91/at91rm9200_devices.c | 9 + arch/arm/mach-at91/at91sam9260.c | 1 + arch/arm/mach-at91/at91sam9261.c | 1 + arch/arm/mach-at91/at91sam9263.c | 1 + arch/arm/mach-at91/at91sam9g45.c | 2 + arch/arm/mach-at91/at91sam9g45_devices.c | 6 - arch/arm/mach-at91/at91sam9rl.c | 2 + arch/arm/mach-at91/include/mach/at91_twi.h | 68 ---- drivers/i2c/busses/Kconfig | 11 +- drivers/i2c/busses/i2c-at91.c | 579 ++++++++++++++++++---------- 12 files changed, 393 insertions(+), 289 deletions(-) delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h
Signature · 1 line
1.7.5.4
PATCH v10 1/4 drivers/i2c/busses/i2c-at91.c: remove broken driver
--- arch/arm/mach-at91/include/mach/at91_twi.h | 68 ------ drivers/i2c/busses/Makefile | 1 - drivers/i2c/busses/i2c-at91.c | 314 ---------------------------- 3 files changed, 0 insertions(+), 383 deletions(-) delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h delete mode 100644 drivers/i2c/busses/i2c-at91.c
arch/arm/mach-at91/include/mach/at91_twi.h deleted +0 -68
@@ -1,68 +0,0 @@ -/* -* arch/arm/mach-at91/include/mach/at91_twi.h -* -* Copyright (C) 2005 Ivan Kokshaysky -* Copyright (C) SAN People -* -* Two-wire Interface (TWI) registers. -* Based on AT91RM9200 datasheet revision E. -* -* This program is free software; you can redistribute it and/or modify -* it under the terms of the GNU General Public License as published by -* the Free Software Foundation; either version 2 of the License, or -* (at your option) any later version. -*/ - -#ifndef AT91_TWI_H -#define AT91_TWI_H - -#define AT91_TWI_CR 0x00/* Control Register */ -#define AT91_TWI_START (1 << 0)/* Send a Start Condition */ -#define AT91_TWI_STOP (1 << 1)/* Send a Stop Condition */ -#define AT91_TWI_MSEN (1 << 2)/* Master Transfer Enable */ -#define AT91_TWI_MSDIS (1 << 3)/* Master Transfer Disable */ -#define AT91_TWI_SVEN (1 << 4)/* Slave Transfer Enable [SAM9260 only] */ -#define AT91_TWI_SVDIS (1 << 5)/* Slave Transfer Disable [SAM9260 only] */ -#define AT91_TWI_SWRST (1 << 7)/* Software Reset */ - -#define AT91_TWI_MMR 0x04/* Master Mode Register */ -#define AT91_TWI_IADRSZ (3 << 8)/* Internal Device Address Size */ -#define AT91_TWI_IADRSZ_NO (0 << 8) -#define AT91_TWI_IADRSZ_1 (1 << 8) -#define AT91_TWI_IADRSZ_2 (2 << 8) -#define AT91_TWI_IADRSZ_3 (3 << 8) -#define AT91_TWI_MREAD (1 << 12)/* Master Read Direction */ -#define AT91_TWI_DADR (0x7f << 16)/* Device Address */ - -#define AT91_TWI_SMR 0x08/* Slave Mode Register [SAM9260 only] */ -#define AT91_TWI_SADR (0x7f << 16)/* Slave Address */ - -#define AT91_TWI_IADR 0x0c/* Internal Address Register */ - -#define AT91_TWI_CWGR 0x10/* Clock Waveform Generator Register */ -#define AT91_TWI_CLDIV (0xff << 0)/* Clock Low Divisor */ -#define AT91_TWI_CHDIV (0xff << 8)/* Clock High Divisor */ -#define AT91_TWI_CKDIV (7 << 16)/* Clock Divider */ - -#define AT91_TWI_SR 0x20/* Status Register */ -#define AT91_TWI_TXCOMP (1 << 0)/* Transmission Complete */ -#define AT91_TWI_RXRDY (1 << 1)/* Receive Holding Register Ready */ -#define AT91_TWI_TXRDY (1 << 2)/* Transmit Holding Register Ready */ -#define AT91_TWI_SVREAD (1 << 3)/* Slave Read [SAM9260 only] */ -#define AT91_TWI_SVACC (1 << 4)/* Slave Access [SAM9260 only] */ -#define AT91_TWI_GACC (1 << 5)/* General Call Access [SAM9260 only] */ -#define AT91_TWI_OVRE (1 << 6)/* Overrun Error [AT91RM9200 only] */ -#define AT91_TWI_UNRE (1 << 7)/* Underrun Error [AT91RM9200 only] */ -#define AT91_TWI_NACK (1 << 8)/* Not Acknowledged */ -#define AT91_TWI_ARBLST (1 << 9)/* Arbitration Lost [SAM9260 only] */ -#define AT91_TWI_SCLWS (1 << 10)/* Clock Wait State [SAM9260 only] */ -#define AT91_TWI_EOSACC (1 << 11)/* End of Slave Address [SAM9260 only] */ - -#define AT91_TWI_IER 0x24/* Interrupt Enable Register */ -#define AT91_TWI_IDR 0x28/* Interrupt Disable Register */ -#define AT91_TWI_IMR 0x2c/* Interrupt Mask Register */ -#define AT91_TWI_RHR 0x30/* Receive Holding Register */ -#define AT91_TWI_THR 0x34/* Transmit Holding Register */ - -#endif -
drivers/i2c/busses/Makefile +0 -1
@@ -28,7 +28,6 @@ obj-$(CONFIG_I2C_HYDRA) += i2c-hydra.o obj-$(CONFIG_I2C_POWERMAC) += i2c-powermac.o # Embedded system I2C/SMBus host controller drivers -obj-$(CONFIG_I2C_AT91) += i2c-at91.o obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o obj-$(CONFIG_I2C_BLACKFIN_TWI) += i2c-bfin-twi.o obj-$(CONFIG_I2C_CPM) += i2c-cpm.o
drivers/i2c/busses/i2c-at91.c deleted +0 -314
314 lines not on this page · raw message
Signature · 1 line
1.7.5.4
PATCH v10 2/4 Replace clk_lookup.con_id with clk_lookup.dev_id entries for twi clk
In reply to Nikolaus VossThe old driver used con_id clock entries. Convert to use dev_id for clock lookup via standard method.
--- arch/arm/mach-at91/at91cap9.c | 1 + arch/arm/mach-at91/at91rm9200.c | 1 + arch/arm/mach-at91/at91sam9260.c | 1 + arch/arm/mach-at91/at91sam9261.c | 1 + arch/arm/mach-at91/at91sam9263.c | 1 + arch/arm/mach-at91/at91sam9g45.c | 2 ++ arch/arm/mach-at91/at91sam9rl.c | 2 ++ 7 files changed, 9 insertions(+), 0 deletions(-)
arch/arm/mach-at91/at91cap9.c +1 -0
@@ -219,6 +219,7 @@ static struct clk_lookup periph_clocks_lookups[] = {CLKDEV_CON_DEV_ID ("t0_clk" ,"atmel_tcb.0" , &tcb_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.0" , &ssc0_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.1" , &ssc1_clk), +CLKDEV_CON_DEV_ID (NULL ,"at91_i2c" , &twi_clk),/* fake hclk clock */ CLKDEV_CON_DEV_ID ("hclk" ,"at91_ohci" , &ohci_clk), CLKDEV_CON_ID("pioA", &pioABCD_clk),
arch/arm/mach-at91/at91rm9200.c +1 -0
@@ -194,6 +194,7 @@ static struct clk_lookup periph_clocks_lookups[] = {CLKDEV_CON_DEV_ID ("pclk" ,"ssc.0" , &ssc0_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.1" , &ssc1_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.2" , &ssc2_clk), +CLKDEV_CON_DEV_ID (NULL ,"at91_i2c" , &twi_clk),/* fake hclk clock */ CLKDEV_CON_DEV_ID ("hclk" ,"at91_ohci" , &ohci_clk), CLKDEV_CON_ID("pioA", &pioA_clk),
arch/arm/mach-at91/at91sam9260.c +1 -0
@@ -200,6 +200,7 @@ static struct clk_lookup periph_clocks_lookups[] = {CLKDEV_CON_DEV_ID ("t1_clk" ,"atmel_tcb.1" , &tc4_clk),CLKDEV_CON_DEV_ID ("t2_clk" ,"atmel_tcb.1" , &tc5_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.0" , &ssc_clk), +CLKDEV_CON_DEV_ID (NULL ,"at91_i2c" , &twi_clk),/* more usart lookup table for DT entries */ CLKDEV_CON_DEV_ID ("usart" ,"fffff200.serial" , &mck), CLKDEV_CON_DEV_ID("usart", "fffb0000.serial", &usart0_clk),
arch/arm/mach-at91/at91sam9261.c +1 -0
@@ -175,6 +175,7 @@ static struct clk_lookup periph_clocks_lookups[] = {CLKDEV_CON_DEV_ID ("pclk" ,"ssc.1" , &ssc1_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.2" , &ssc2_clk),CLKDEV_CON_DEV_ID ("hclk" ,"at91_ohci" , &hck0), +CLKDEV_CON_DEV_ID (NULL ,"at91_i2c" , &twi_clk),CLKDEV_CON_ID ("pioA" , &pioA_clk),CLKDEV_CON_ID ("pioB" , &pioB_clk), CLKDEV_CON_ID("pioC", &pioC_clk),
arch/arm/mach-at91/at91sam9263.c +1 -0
@@ -190,6 +190,7 @@ static struct clk_lookup periph_clocks_lookups[] = {CLKDEV_CON_DEV_ID ("spi_clk" ,"atmel_spi.0" , &spi0_clk),CLKDEV_CON_DEV_ID ("spi_clk" ,"atmel_spi.1" , &spi1_clk),CLKDEV_CON_DEV_ID ("t0_clk" ,"atmel_tcb.0" , &tcb_clk), +CLKDEV_CON_DEV_ID (NULL ,"at91_i2c" , &twi_clk),/* fake hclk clock */ CLKDEV_CON_DEV_ID ("hclk" ,"at91_ohci" , &ohci_clk), CLKDEV_CON_ID("pioA", &pioA_clk),
arch/arm/mach-at91/at91sam9g45.c +2 -0
@@ -220,6 +220,8 @@ static struct clk_lookup periph_clocks_lookups[] = {CLKDEV_CON_DEV_ID ("spi_clk" ,"atmel_spi.1" , &spi1_clk),CLKDEV_CON_DEV_ID ("t0_clk" ,"atmel_tcb.0" , &tcb0_clk),CLKDEV_CON_DEV_ID ("t0_clk" ,"atmel_tcb.1" , &tcb0_clk), +CLKDEV_CON_DEV_ID (NULL ,"at91_i2c.0" , &twi0_clk), +CLKDEV_CON_DEV_ID (NULL ,"at91_i2c.1" , &twi1_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.0" , &ssc0_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.1" , &ssc1_clk), CLKDEV_CON_DEV_ID(NULL, "atmel-trng", &trng_clk),
arch/arm/mach-at91/at91sam9rl.c +2 -0
@@ -183,6 +183,8 @@ static struct clk_lookup periph_clocks_lookups[] = {CLKDEV_CON_DEV_ID ("t2_clk" ,"atmel_tcb.0" , &tc2_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.0" , &ssc0_clk),CLKDEV_CON_DEV_ID ("pclk" ,"ssc.1" , &ssc1_clk), +CLKDEV_CON_DEV_ID (NULL ,"at91_i2c.0" , &twi0_clk), +CLKDEV_CON_DEV_ID (NULL ,"at91_i2c.1" , &twi1_clk),CLKDEV_CON_ID ("pioA" , &pioA_clk),CLKDEV_CON_ID ("pioB" , &pioB_clk), CLKDEV_CON_ID("pioC", &pioC_clk),
Signature · 1 line
1.7.5.4
PATCH v10 3/4 drivers/i2c/busses/i2c-at91.c: add new driver
In reply to Nikolaus VossThis driver has the following properties compared to the old driver:
1. Support for multiple interfaces.
2. Interrupt driven I/O as opposed to polling/busy waiting.
3. Support for _one_ repeated start (Sr) condition, which is enough for most real-world applications including all SMBus transfer types. (The hardware does not support issuing arbitrary Sr conditions on the
bus.)
testing: SoC: at91sam9g45
- BQ20Z80 battery SMBus client.
- on a 2.6.38 kernel with several i2c clients (temp-sensor, audio-codec, touchscreen-controller, w1-bridge, io-expanders)
---
v10: - applied fix for RXRDY overrun bug submitted by Hubert Feurstein
- applied fix for calculating twi_clk
v9: - merge i2c-at91.c patches to single patch
- rewrite cwgr reg after timeout
v8: - remove local include
- remove cpu_is_rm9200() and put twi hw bug info in platform_device
- use readl/writel_relaxed instead of __raw_readl/writel
v7: i) fix bug if internal address > 1 byte
ii) send stop when len == 1 (both reported by Carsten Behling)
v6: support for I2C_SMBUS_BLOCK_DATA transfers.
Better use of clk_(un)prepare().
More sensible transfer timeout.
v5: Another round of review comments from Ryan Mallon, Felipe Balbi
and Russell King: convert twi clk to use .dev_id, cleanups
v4: Integrated more review comments from Ryan Mallon and Felipe Balbi:
Moved register include file to local include, code cleanups
v3: Integrated review comments from Ryan Mallon and Felipe Balbi
v2: Fixed whitespace issue
arch/arm/mach-at91/at91rm9200_devices.c | 9 + drivers/i2c/busses/Kconfig | 11 +- drivers/i2c/busses/Makefile | 1 + drivers/i2c/busses/i2c-at91.c | 477 +++++++++++++++++++++++++++++++ 4 files changed, 491 insertions(+), 7 deletions(-) create mode 100644 drivers/i2c/busses/i2c-at91.c
arch/arm/mach-at91/at91rm9200_devices.c +9 -0
@@ -493,9 +493,18 @@ static struct resource twi_resources[] = { }, }; +static const struct platform_device_id twi_id = { +/* +* driver_data is "1" for hardware with ckdiv upper limit == 5 +* (AT91RM9200 erratum 22), "0" for twi modules without this bug +*/ + .driver_data =1 , +}; +static struct platform_device at91rm9200_twi_device = { .name ="at91_i2c" , .id =-1 , + .id_entry = &twi_id, .resource = twi_resources, .num_resources =ARRAY_SIZE (twi_resources), };
drivers/i2c/busses/Kconfig +4 -7
@@ -285,18 +285,15 @@ comment "I2C system bus drivers (mostly embedded / system-on-chip)" config I2C_AT91 tristate "Atmel AT91 I2C Two-Wire interface (TWI)" - depends on ARCH_AT91 && EXPERIMENTAL && BROKEN + depends on ARCH_AT91 && EXPERIMENTAL help This supports the use of the I2C interface on Atmel AT91 processors. - This driver is BROKEN because the controller which it uses - will easily trigger RX overrun and TX underrun errors. Using - low I2C clock rates may partially work around those issues - on some systems. Another serious problem is that there is no - documented way to issue repeated START conditions, as needed + A serious problem is that there is no documented way to issue + repeated START conditions for more than two messages, as needed to support combined I2C messages. Use the i2c-gpio driver - unless your system can cope with those limitations. + unless your system can cope with this limitation. config I2C_AU1550 tristate "Au1550/Au1200/Au1300 SMBus interface"
drivers/i2c/busses/Makefile +1 -0
@@ -28,6 +28,7 @@ obj-$(CONFIG_I2C_HYDRA) += i2c-hydra.o obj-$(CONFIG_I2C_POWERMAC) += i2c-powermac.o # Embedded system I2C/SMBus host controller drivers +obj-$(CONFIG_I2C_AT91) += i2c-at91.o obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o obj-$(CONFIG_I2C_BLACKFIN_TWI) += i2c-bfin-twi.o obj-$(CONFIG_I2C_CPM) += i2c-cpm.o
drivers/i2c/busses/i2c-at91.c new file +477 -0
477 lines not on this page · raw message
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1.7.5.4
PATCH v10 4/4 G45 TWI: remove open drain setting for twi function gpios
In reply to Nikolaus VossThe G45 datasheets explicitly states that setting the open drain property on peripheral function gpios is not allowed. (How about other A91 chips?)
--- arch/arm/mach-at91/at91sam9g45_devices.c | 6 ------ 1 files changed, 0 insertions(+), 6 deletions(-)
arch/arm/mach-at91/at91sam9g45_devices.c +0 -6
@@ -688,18 +688,12 @@ void __init at91_add_device_i2c(short i2c_id, struct i2c_board_info *devices, in/* pins used for TWI interface */ if (i2c_id ==0 ) {at91_set_A_periph (AT91_PIN_PA20 ,0 );/* TWD */ -at91_set_multi_drive (AT91_PIN_PA20 ,1 ); -at91_set_A_periph (AT91_PIN_PA21 ,0 );/* TWCK */ -at91_set_multi_drive (AT91_PIN_PA21 ,1 );platform_device_register (&at91sam9g45_twi0_device); }else {at91_set_A_periph (AT91_PIN_PB10 ,0 );/* TWD */ -at91_set_multi_drive (AT91_PIN_PB10 ,1 ); -at91_set_A_periph (AT91_PIN_PB11 ,0 );/* TWCK */ -at91_set_multi_drive (AT91_PIN_PB11 ,1 );platform_device_register (&at91sam9g45_twi1_device); }
Signature · 1 line
1.7.5.4