i2c-s3c2410: Simplify bus frequency calculation
The platform data for the i2c-s3c2410 driver used to allow a min, max and desired frequency for the I2C bus. This patch reduces it to simply a desired frequency ceiling and corrects all the uses of the platform data appropriately. This means, for example, that on a system with a 66MHz fclk, a request for 100KHz will achieve 65KHz which is safe and acceptable, rather than 378KHz which it would have achieved without this change. Signed-off-by: Simtec Linux Team <linux@simtec.co.uk> Signed-off-by: Daniel Silverstone <dsilvers@simtec.co.uk> [ben-linux@fluff.org: tidy subject and description] Signed-off-by: Ben Dooks <ben-linux@fluff.org>
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@ -409,8 +409,7 @@ static struct platform_device bast_sio = {
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static struct s3c2410_platform_i2c __initdata bast_i2c_info = {
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.flags = 0,
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.slave_addr = 0x10,
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.bus_freq = 100*1000,
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.max_freq = 130*1000,
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.frequency = 100*1000,
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};
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/* Asix AX88796 10/100 ethernet controller */
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@ -340,8 +340,7 @@ static struct platform_device *n35_devices[] __initdata = {
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static struct s3c2410_platform_i2c n30_i2ccfg = {
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.flags = 0,
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.slave_addr = 0x10,
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.bus_freq = 10*1000,
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.max_freq = 10*1000,
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.frequency = 10*1000,
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};
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/* Lots of hardcoded stuff, but it sets up the hardware in a useful
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@ -453,8 +453,7 @@ static struct spi_board_info __initdata jive_spi_devs[] = {
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/* I2C bus and device configuration. */
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static struct s3c2410_platform_i2c jive_i2c_cfg __initdata = {
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.max_freq = 80 * 1000,
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.bus_freq = 50 * 1000,
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.frequency = 80 * 1000,
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.flags = S3C_IICFLG_FILTER,
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.sda_delay = 2,
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};
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@ -1,6 +1,6 @@
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/* linux/arch/arm/plat-s3c/dev-i2c0.c
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*
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* Copyright 2008 Simtec Electronics
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* Copyright 2008,2009 Simtec Electronics
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* Ben Dooks <ben@simtec.co.uk>
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* http://armlinux.simtec.co.uk/
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*
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@ -50,8 +50,7 @@ struct platform_device s3c_device_i2c0 = {
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static struct s3c2410_platform_i2c default_i2c_data0 __initdata = {
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.flags = 0,
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.slave_addr = 0x10,
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.bus_freq = 100*1000,
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.max_freq = 400*1000,
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.frequency = 100*1000,
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.sda_delay = 100,
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};
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@ -1,6 +1,6 @@
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/* linux/arch/arm/plat-s3c/dev-i2c1.c
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*
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* Copyright 2008 Simtec Electronics
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* Copyright 2008,2009 Simtec Electronics
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* Ben Dooks <ben@simtec.co.uk>
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* http://armlinux.simtec.co.uk/
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*
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@ -47,8 +47,7 @@ static struct s3c2410_platform_i2c default_i2c_data1 __initdata = {
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.flags = 0,
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.bus_num = 1,
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.slave_addr = 0x10,
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.bus_freq = 100*1000,
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.max_freq = 400*1000,
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.frequency = 100*1000,
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.sda_delay = 100,
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};
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@ -1,9 +1,9 @@
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/* arch/arm/mach-s3c2410/include/mach/iic.h
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/* arch/arm/plat-s3c/include/plat/iic.h
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*
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* Copyright (c) 2004 Simtec Electronics
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* Copyright 2004,2009 Simtec Electronics
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* Ben Dooks <ben@simtec.co.uk>
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*
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* S3C2410 - I2C Controller platfrom_device info
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* S3C - I2C Controller platform_device info
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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@ -15,19 +15,24 @@
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#define S3C_IICFLG_FILTER (1<<0) /* enable s3c2440 filter */
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/* Notes:
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* 1) All frequencies are expressed in Hz
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* 2) A value of zero is `do not care`
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*/
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/**
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* struct s3c2410_platform_i2c - Platform data for s3c I2C.
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* @bus_num: The bus number to use (if possible).
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* @flags: Any flags for the I2C bus (E.g. S3C_IICFLK_FILTER).
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* @slave_addr: The I2C address for the slave device (if enabled).
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* @frequency: The desired frequency in Hz of the bus. This is
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* guaranteed to not be exceeded. If the caller does
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* not care, use zero and the driver will select a
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* useful default.
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* @sda_delay: The delay (in ns) applied to SDA edges.
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* @cfg_gpio: A callback to configure the pins for I2C operation.
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*/
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struct s3c2410_platform_i2c {
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int bus_num; /* bus number to use */
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int bus_num;
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unsigned int flags;
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unsigned int slave_addr; /* slave address for controller */
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unsigned long bus_freq; /* standard bus frequency */
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unsigned long max_freq; /* max frequency for the bus */
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unsigned long min_freq; /* min frequency for the bus */
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unsigned int sda_delay; /* pclks (s3c2440 only) */
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unsigned int slave_addr;
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unsigned long frequency;
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unsigned int sda_delay;
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void (*cfg_gpio)(struct platform_device *dev);
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};
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@ -1,6 +1,6 @@
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/* linux/drivers/i2c/busses/i2c-s3c2410.c
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*
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* Copyright (C) 2004,2005 Simtec Electronics
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* Copyright (C) 2004,2005,2009 Simtec Electronics
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* Ben Dooks <ben@simtec.co.uk>
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*
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* S3C2410 I2C Controller
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@ -590,18 +590,6 @@ static int s3c24xx_i2c_calcdivisor(unsigned long clkin, unsigned int wanted,
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return clkin / (calc_divs * calc_div1);
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}
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/* freq_acceptable
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*
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* test wether a frequency is within the acceptable range of error
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*/
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static inline int freq_acceptable(unsigned int freq, unsigned int wanted)
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{
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int diff = freq - wanted;
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return diff >= -2 && diff <= 2;
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}
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/* s3c24xx_i2c_clockrate
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*
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* work out a divisor for the user requested frequency setting,
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@ -614,44 +602,28 @@ static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
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struct s3c2410_platform_i2c *pdata = i2c->dev->platform_data;
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unsigned long clkin = clk_get_rate(i2c->clk);
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unsigned int divs, div1;
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unsigned long target_frequency;
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u32 iiccon;
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int freq;
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int start, end;
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i2c->clkrate = clkin;
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clkin /= 1000; /* clkin now in KHz */
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dev_dbg(i2c->dev, "pdata %p, freq %lu %lu..%lu\n",
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pdata, pdata->bus_freq, pdata->min_freq, pdata->max_freq);
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dev_dbg(i2c->dev, "pdata desired frequency %lu\n", pdata->frequency);
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if (pdata->bus_freq != 0) {
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freq = s3c24xx_i2c_calcdivisor(clkin, pdata->bus_freq/1000,
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&div1, &divs);
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if (freq_acceptable(freq, pdata->bus_freq/1000))
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goto found;
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target_frequency = pdata->frequency ? pdata->frequency : 100000;
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target_frequency /= 1000; /* Target frequency now in KHz */
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freq = s3c24xx_i2c_calcdivisor(clkin, target_frequency, &div1, &divs);
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if (freq > target_frequency) {
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dev_err(i2c->dev,
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"Unable to achieve desired frequency %luKHz." \
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" Lowest achievable %dKHz\n", target_frequency, freq);
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return -EINVAL;
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}
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/* ok, we may have to search for something suitable... */
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start = (pdata->max_freq == 0) ? pdata->bus_freq : pdata->max_freq;
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end = pdata->min_freq;
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start /= 1000;
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end /= 1000;
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/* search loop... */
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for (; start > end; start--) {
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freq = s3c24xx_i2c_calcdivisor(clkin, start, &div1, &divs);
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if (freq_acceptable(freq, start))
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goto found;
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}
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/* cannot find frequency spec */
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return -EINVAL;
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found:
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*got = freq;
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iiccon = readl(i2c->regs + S3C2410_IICCON);
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