ARM: S3C2410: CPUFREQ: Add io-timing support.

Add io-timing support for frequency scaling on the S3C2410 SoC.

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

3 files changed, 442 insertions, 0 deletions

diff --git a/arch/arm/plat-s3c24xx/Kconfig b/arch/arm/plat-s3c24xx/Kconfig
index 5b0bc91..d82d30c 100644
--- a/arch/arm/plat-s3c24xx/Kconfig
+++ b/arch/arm/plat-s3c24xx/Kconfig
@@ -107,6 +107,15 @@ config S3C24XX_SPI_BUS1_GPG5_GPG6_GPG7
 
 # common code for s3c24xx based machines, such as the SMDKs.
 
+# cpu frequency items common between s3c2410 and s3c2440/s3c2442
+
+config S3C2410_IOTIMING
+	bool
+	depends on CPU_FREQ_S3C24XX
+	help
+	  Internal node to select io timing code that is common to the s3c2410
+	  and s3c2440/s3c2442 cpu frequency support.
+
 config MACH_SMDK
 	bool
 	help
diff --git a/arch/arm/plat-s3c24xx/Makefile b/arch/arm/plat-s3c24xx/Makefile
index 1f6add5..6f9afd1 100644
--- a/arch/arm/plat-s3c24xx/Makefile
+++ b/arch/arm/plat-s3c24xx/Makefile
@@ -35,6 +35,7 @@ obj-$(CONFIG_S3C24XX_PWM)	+= pwm.o
 obj-$(CONFIG_S3C2410_CLOCK)	+= s3c2410-clock.o
 obj-$(CONFIG_S3C2410_DMA)	+= dma.o
 obj-$(CONFIG_S3C24XX_ADC)	+= adc.o
+obj-$(CONFIG_S3C2410_IOTIMING)	+= s3c2410-iotiming.o
 
 # device specific setup and/or initialisation
 obj-$(CONFIG_ARCH_S3C2410)	+= setup-i2c.o
diff --git a/arch/arm/plat-s3c24xx/s3c2410-iotiming.c b/arch/arm/plat-s3c24xx/s3c2410-iotiming.c
new file mode 100644
index 0000000..26fe212
--- /dev/null
+++ b/arch/arm/plat-s3c24xx/s3c2410-iotiming.c
@@ -0,0 +1,432 @@
+/* linux/arch/arm/plat-s3c24xx/s3c2410-iotiming.c
+ *
+ * Copyright (c) 2006,2008,2009 Simtec Electronics
+ *	http://armlinux.simtec.co.uk/
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * S3C24XX CPU Frequency scaling - IO timing for S3C2410/S3C2440/S3C2442
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/cpufreq.h>
+#include <linux/io.h>
+
+#include <mach/map.h>
+#include <mach/regs-mem.h>
+#include <mach/regs-clock.h>
+
+#include <plat/cpu-freq-core.h>
+
+#define print_ns(x) ((x) / 10), ((x) % 10)
+
+/**
+ * s3c2410_print_timing - print bank timing data for debug purposes
+ * @pfx: The prefix to put on the output
+ * @timings: The timing inforamtion to print.
+*/
+static void s3c2410_print_timing(const char *pfx,
+				 struct s3c_iotimings *timings)
+{
+	struct s3c2410_iobank_timing *bt;
+	int bank;
+
+	for (bank = 0; bank < MAX_BANKS; bank++) {
+		bt = timings->bank[bank].io_2410;
+		if (!bt)
+			continue;
+
+		printk(KERN_DEBUG "%s %d: Tacs=%d.%d, Tcos=%d.%d, Tacc=%d.%d, "
+		       "Tcoh=%d.%d, Tcah=%d.%d\n", pfx, bank,
+		       print_ns(bt->tacs),
+		       print_ns(bt->tcos),
+		       print_ns(bt->tacc),
+		       print_ns(bt->tcoh),
+		       print_ns(bt->tcah));
+	}
+}
+
+/**
+ * bank_reg - convert bank number to pointer to the control register.
+ * @bank: The IO bank number.
+ */
+static inline void __iomem *bank_reg(unsigned int bank)
+{
+	return S3C2410_BANKCON0 + (bank << 2);
+}
+
+/**
+ * bank_is_io - test whether bank is used for IO
+ * @bankcon: The bank control register.
+ *
+ * This is a simplistic test to see if any BANKCON[x] is not an IO
+ * bank. It currently does not take into account whether BWSCON has
+ * an illegal width-setting in it, or if the pin connected to nCS[x]
+ * is actually being handled as a chip-select.
+ */
+static inline int bank_is_io(unsigned long bankcon)
+{
+	return !(bankcon & S3C2410_BANKCON_SDRAM);
+}
+
+/**
+ * to_div - convert cycle time to divisor
+ * @cyc: The cycle time, in 10ths of nanoseconds.
+ * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
+ *
+ * Convert the given cycle time into the divisor to use to obtain it from
+ * HCLK.
+*/
+static inline unsigned int to_div(unsigned int cyc, unsigned int hclk_tns)
+{
+	if (cyc == 0)
+		return 0;
+
+	return DIV_ROUND_UP(cyc, hclk_tns);
+}
+
+/**
+ * calc_0124 - calculate divisor control for divisors that do /0, /1. /2 and /4
+ * @cyc: The cycle time, in 10ths of nanoseconds.
+ * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
+ * @v: Pointer to register to alter.
+ * @shift: The shift to get to the control bits.
+ *
+ * Calculate the divisor, and turn it into the correct control bits to
+ * set in the result, @v.
+ */
+static unsigned int calc_0124(unsigned int cyc, unsigned long hclk_tns,
+			      unsigned long *v, int shift)
+{
+	unsigned int div = to_div(cyc, hclk_tns);
+	unsigned long val;
+
+	s3c_freq_iodbg("%s: cyc=%d, hclk=%lu, shift=%d => div %d\n",
+		       __func__, cyc, hclk_tns, shift, div);
+
+	switch (div) {
+	case 0:
+		val = 0;
+		break;
+	case 1:
+		val = 1;
+		break;
+	case 2:
+		val = 2;
+		break;
+	case 3:
+	case 4:
+		val = 3;
+		break;
+	default:
+		return -1;
+	}
+
+	*v |= val << shift;
+	return 0;
+}
+
+int calc_tacp(unsigned int cyc, unsigned long hclk, unsigned long *v)
+{
+	/* Currently no support for Tacp calculations. */
+	return 0;
+}
+
+/**
+ * calc_tacc - calculate divisor control for tacc.
+ * @cyc: The cycle time, in 10ths of nanoseconds.
+ * @nwait_en: IS nWAIT enabled for this bank.
+ * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
+ * @v: Pointer to register to alter.
+ *
+ * Calculate the divisor control for tACC, taking into account whether
+ * the bank has nWAIT enabled. The result is used to modify the value
+ * pointed to by @v.
+*/
+static int calc_tacc(unsigned int cyc, int nwait_en,
+		     unsigned long hclk_tns, unsigned long *v)
+{
+	unsigned int div = to_div(cyc, hclk_tns);
+	unsigned long val;
+
+	s3c_freq_iodbg("%s: cyc=%u, nwait=%d, hclk=%lu => div=%u\n",
+		       __func__, cyc, nwait_en, hclk_tns, div);
+
+	/* if nWait enabled on an bank, Tacc must be at-least 4 cycles. */
+	if (nwait_en && div < 4)
+		div = 4;
+
+	switch (div) {
+	case 0:
+		val = 0;
+		break;
+
+	case 1:
+	case 2:
+	case 3:
+	case 4:
+		val = div - 1;
+		break;
+
+	case 5:
+	case 6:
+		val = 4;
+		break;
+
+	case 7:
+	case 8:
+		val = 5;
+		break;
+
+	case 9:
+	case 10:
+		val = 6;
+		break;
+
+	case 11:
+	case 12:
+	case 13:
+	case 14:
+		val = 7;
+		break;
+
+	default:
+		return -1;
+	}
+
+	*v |= val << 8;
+	return 0;
+}
+
+/**
+ * s3c2410_calc_bank - calculate bank timing infromation
+ * @cfg: The configuration we need to calculate for.
+ * @bt: The bank timing information.
+ *
+ * Given the cycle timine for a bank @bt, calculate the new BANKCON
+ * setting for the @cfg timing. This updates the timing information
+ * ready for the cpu frequency change.
+ */
+static int s3c2410_calc_bank(struct s3c_cpufreq_config *cfg,
+			     struct s3c2410_iobank_timing *bt)
+{
+	unsigned long hclk = cfg->freq.hclk_tns;
+	unsigned long res;
+	int ret;
+
+	res  = bt->bankcon;
+	res &= (S3C2410_BANKCON_SDRAM | S3C2410_BANKCON_PMC16);
+
+	/* tacp: 2,3,4,5 */
+	/* tcah: 0,1,2,4 */
+	/* tcoh: 0,1,2,4 */
+	/* tacc: 1,2,3,4,6,7,10,14 (>4 for nwait) */
+	/* tcos: 0,1,2,4 */
+	/* tacs: 0,1,2,4 */
+
+	ret  = calc_0124(bt->tacs, hclk, &res, S3C2410_BANKCON_Tacs_SHIFT);
+	ret |= calc_0124(bt->tcos, hclk, &res, S3C2410_BANKCON_Tcos_SHIFT);
+	ret |= calc_0124(bt->tcah, hclk, &res, S3C2410_BANKCON_Tcah_SHIFT);
+	ret |= calc_0124(bt->tcoh, hclk, &res, S3C2410_BANKCON_Tcoh_SHIFT);
+
+	if (ret)
+		return -EINVAL;
+
+	ret |= calc_tacp(bt->tacp, hclk, &res);
+	ret |= calc_tacc(bt->tacc, bt->nwait_en, hclk, &res);
+
+	if (ret)
+		return -EINVAL;
+
+	bt->bankcon = res;
+	return 0;
+}
+
+static unsigned int tacc_tab[] = {
+	[0]	= 1,
+	[1]	= 2,
+	[2]	= 3,
+	[3]	= 4,
+	[4]	= 6,
+	[5]	= 9,
+	[6]	= 10,
+	[7]	= 14,
+};
+
+/**
+ * get_tacc - turn tACC value into cycle time
+ * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
+ * @val: The bank timing register value, shifed down.
+ */
+static unsigned int get_tacc(unsigned long hclk_tns,
+			     unsigned long val)
+{
+	val &= 7;
+	return hclk_tns * tacc_tab[val];
+}
+
+/**
+ * get_0124 - turn 0/1/2/4 divider into cycle time
+ * @hclk_tns: The cycle time for HCLK, in 10ths of nanoseconds.
+ * @val: The bank timing register value, shifed down.
+ */
+static unsigned int get_0124(unsigned long hclk_tns,
+			     unsigned long val)
+{
+	val &= 3;
+	return hclk_tns * ((val == 3) ? 4 : val);
+}
+
+/**
+ * s3c2410_iotiming_getbank - turn BANKCON into cycle time information
+ * @cfg: The frequency configuration
+ * @bt: The bank timing to fill in (uses cached BANKCON)
+ *
+ * Given the BANKCON setting in @bt and the current frequency settings
+ * in @cfg, update the cycle timing information.
+ */
+void s3c2410_iotiming_getbank(struct s3c_cpufreq_config *cfg,
+			      struct s3c2410_iobank_timing *bt)
+{
+	unsigned long bankcon = bt->bankcon;
+	unsigned long hclk = cfg->freq.hclk_tns;
+
+	bt->tcah = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tcah_SHIFT);
+	bt->tcoh = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tcoh_SHIFT);
+	bt->tcos = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tcos_SHIFT);
+	bt->tacs = get_0124(hclk, bankcon >> S3C2410_BANKCON_Tacs_SHIFT);
+	bt->tacc = get_tacc(hclk, bankcon >> S3C2410_BANKCON_Tacc_SHIFT);
+}
+
+/**
+ * s3c2410_iotiming_calc - Calculate bank timing for frequency change.
+ * @cfg: The frequency configuration
+ * @iot: The IO timing information to fill out.
+ *
+ * Calculate the new values for the banks in @iot based on the new
+ * frequency information in @cfg. This is then used by s3c2410_iotiming_set()
+ * to update the timing when necessary.
+ */
+int s3c2410_iotiming_calc(struct s3c_cpufreq_config *cfg,
+			  struct s3c_iotimings *iot)
+{
+	struct s3c2410_iobank_timing *bt;
+	unsigned long bankcon;
+	int bank;
+	int ret;
+
+	for (bank = 0; bank < MAX_BANKS; bank++) {
+		bankcon = __raw_readl(bank_reg(bank));
+		bt = iot->bank[bank].io_2410;
+
+		if (!bt)
+			continue;
+
+		bt->bankcon = bankcon;
+
+		ret = s3c2410_calc_bank(cfg, bt);
+		if (ret) {
+			printk(KERN_ERR "%s: cannot calculate bank %d io\n",
+			       __func__, bank);
+			goto err;
+		}
+
+		s3c_freq_iodbg("%s: bank %d: con=%08lx\n",
+			       __func__, bank, bt->bankcon);
+	}
+
+	return 0;
+ err:
+	return ret;
+}
+
+/**
+ * s3c2410_iotiming_set - set the IO timings from the given setup.
+ * @cfg: The frequency configuration
+ * @iot: The IO timing information to use.
+ *
+ * Set all the currently used IO bank timing information generated
+ * by s3c2410_iotiming_calc() once the core has validated that all
+ * the new values are within permitted bounds.
+ */
+void s3c2410_iotiming_set(struct s3c_cpufreq_config *cfg,
+			  struct s3c_iotimings *iot)
+{
+	struct s3c2410_iobank_timing *bt;
+	int bank;
+
+	/* set the io timings from the specifier */
+
+	for (bank = 0; bank < MAX_BANKS; bank++) {
+		bt = iot->bank[bank].io_2410;
+		if (!bt)
+			continue;
+
+		__raw_writel(bt->bankcon, bank_reg(bank));
+	}
+}
+
+/**
+ * s3c2410_iotiming_get - Get the timing information from current registers.
+ * @cfg: The frequency configuration
+ * @timings: The IO timing information to fill out.
+ *
+ * Calculate the @timings timing information from the current frequency
+ * information in @cfg, and the new frequency configur
+ * through all the IO banks, reading the state and then updating @iot
+ * as necessary.
+ *
+ * This is used at the moment on initialisation to get the current
+ * configuration so that boards do not have to carry their own setup
+ * if the timings are correct on initialisation.
+ */
+
+int s3c2410_iotiming_get(struct s3c_cpufreq_config *cfg,
+			 struct s3c_iotimings *timings)
+{
+	struct s3c2410_iobank_timing *bt;
+	unsigned long bankcon;
+	unsigned long bwscon;
+	int bank;
+
+	bwscon = __raw_readl(S3C2410_BWSCON);
+
+	/* look through all banks to see what is currently set. */
+
+	for (bank = 0; bank < MAX_BANKS; bank++) {
+		bankcon = __raw_readl(bank_reg(bank));
+
+		if (!bank_is_io(bankcon))
+			continue;
+
+		s3c_freq_iodbg("%s: bank %d: con %08lx\n",
+			       __func__, bank, bankcon);
+
+		bt = kzalloc(sizeof(struct s3c2410_iobank_timing), GFP_KERNEL);
+		if (!bt) {
+			printk(KERN_ERR "%s: no memory for bank\n", __func__);
+			return -ENOMEM;
+		}
+
+		/* find out in nWait is enabled for bank. */
+
+		if (bank != 0) {
+			unsigned long tmp  = S3C2410_BWSCON_GET(bwscon, bank);
+			if (tmp & S3C2410_BWSCON_WS)
+				bt->nwait_en = 1;
+		}
+
+		timings->bank[bank].io_2410 = bt;
+		bt->bankcon = bankcon;
+
+		s3c2410_iotiming_getbank(cfg, bt);
+	}
+
+	s3c2410_print_timing("get", timings);
+	return 0;
+}