* [PATCH v4 2/4] drivers/i2c/busses/i2c-at91.c: add new driver
[not found] ` <fc7ccca66f0ffea1aa9c0409162b4a66974c46b3.1320853921.git.n.voss@weinmann.de>
@ 2011-11-09 19:59 ` Felipe Balbi
2011-11-09 22:22 ` Ryan Mallon
0 siblings, 1 reply; 2+ messages in thread
From: Felipe Balbi @ 2011-11-09 19:59 UTC (permalink / raw)
To: linux-arm-kernel
Hi,
On Tue, Nov 08, 2011 at 11:49:46AM +0100, Nikolaus Voss wrote:
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index e8a1852..fba6da6 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -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
> diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
> new file mode 100644
> index 0000000..5f4be34
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-at91.c
> @@ -0,0 +1,417 @@
> +/*
> + i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
> +
> + Copyright (C) 2011 Nikolaus Voss <n.voss@weinmann.de>
> +
> + Evolved from original work by:
> + Copyright (C) 2004 Rick Bronson
> + Converted to 2.6 by Andrew Victor <andrew@sanpeople.com>
> +
> + Borrowed heavily from original work by:
> + Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
> +
> + 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.
> +*/
wrong multi-line comment style.
> +static void at91_set_twi_clock(struct at91_twi_dev *dev)
this should be __devinit as it's only used by at91_twi_hwinit()
> +{
> + unsigned long cdiv, ckdiv;
> +
> + /* Calcuate clock dividers and round up */
typo: calculate.
> + cdiv = (clk_get_rate(dev->clk) / (2 * TWI_CLOCK_HZ)) - 3 + 1;
DIV_ROUND_UP() ??
> + ckdiv = 0;
> + while (cdiv > 255) {
> + ckdiv++;
> + cdiv = cdiv >> 1;
> + }
> +
> + if (cpu_is_at91rm9200() && (ckdiv > 5)) {
> + dev_err(dev->dev, "AT91RM9200 Erratum #22: using ckdiv = 5.\n");
is it really an error ? Or would it be enough as dev_dbg() ?
> +static int at91_do_twi_transfer(struct at91_twi_dev *dev, bool is_read)
> +{
> + int ret;
> +
> + INIT_COMPLETION(dev->cmd_complete);
> + if (is_read) {
> + if (!dev->buf_len)
> + at91_twi_write(dev, AT91_TWI_CR,
> + AT91_TWI_START | AT91_TWI_STOP);
> + else
> + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_START);
> + at91_twi_write(dev, AT91_TWI_IER,
> + AT91_TWI_TXCOMP | AT91_TWI_RXRDY);
> + } else {
> + at91_twi_write_next_byte(dev);
> + at91_twi_write(dev, AT91_TWI_IER,
> + AT91_TWI_TXCOMP | AT91_TWI_TXRDY);
> + }
> +
> + ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
> + dev->adapter.timeout);
> + if (ret == 0) {
> + dev_err(dev->dev, "controller timed out\n");
> + at91_init_twi_bus(dev);
> + return -ETIMEDOUT;
> + }
> + if (dev->transfer_status & AT91_TWI_NACK) {
> + dev_dbg(dev->dev, "received nack\n");
> + return -ENODEV;
not sure error code matches here. If the HW replies with NACK you tell
your users there's no I2C adapter ? Sounds a bit weird to me...
> +static int __devinit at91_twi_probe(struct platform_device *pdev)
> +{
> + struct at91_twi_dev *dev;
> + struct resource *mem, *irq, *ioarea;
> + int rc;
> +
> + mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!mem)
> + return -ENODEV;
> +
> + irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
int irq = platform_get_irq(pdev, 0), would work better for you. In case
of error it will return -ENXIO
> + if (!irq)
> + return -ENODEV;
> +
> + ioarea = request_mem_region(mem->start, resource_size(mem), pdev->name);
> + if (!ioarea)
> + return -EBUSY;
> +
> + dev = kzalloc(sizeof(struct at91_twi_dev), GFP_KERNEL);
sizeof(*dev) would allow you to change the type of dev without having to
patch this line. Quite unlikely, I know, but still...
--
balbi
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