linux-kernel - [PATCH v9 0/4] AT91: replace broken TWI driver i2c-at91.c

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Message-Id: <cover.1322479017a.git.n.voss@weinmann.de>
Date:	Mon, 19 Mar 2012 16:07:10 +0100
From:	Nikolaus Voss <n.voss@...nmann.de>
To:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-i2c@...r.kernel.org
Cc:	nicolas.ferre@...el.com, ben-linux@...ff.org, balbi@...com,
	<h.feurstein@...il.com>, <rmallon@...il.com>
Subject: [PATCH v9 0/4] 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.

Signed-off-by: Nikolaus Voss <n.voss@...nmann.de>
Reviewed-by: Felipe Balbi <balbi@...com>
Tested-by: Hubert Feurstein <h.feurstein@...il.com>

v9: i) merge i2c-at91.c patches to single patch
    ii) rewrite cwgr reg after timeout to reenable the right twi clock
v8: i) remove local include
    ii) remove cpu_is_rm9200() and put twi hw bug info in platform_device
    iii) 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              |  561 +++++++++++++++++-----------
 12 files changed, 373 insertions(+), 291 deletions(-)
 delete mode 100644 arch/arm/mach-at91/include/mach/at91_twi.h

-- 
1.7.5.4

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