1 files changed, 438 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq-nforce2.c b/drivers/cpufreq/cpufreq-nforce2.c
new file mode 100644
index 000000000..f7a7bcf6f
--- /dev/null
+++ b/drivers/cpufreq/cpufreq-nforce2.c
@@ -0,0 +1,438 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * (C) 2004-2006  Sebastian Witt <se.witt@gmx.net>
+ *
+ *  Based upon reverse engineered information
+ *
+ *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/pci.h>
+#include <linux/delay.h>
+
+#define NFORCE2_XTAL 25
+#define NFORCE2_BOOTFSB 0x48
+#define NFORCE2_PLLENABLE 0xa8
+#define NFORCE2_PLLREG 0xa4
+#define NFORCE2_PLLADR 0xa0
+#define NFORCE2_PLL(mul, div) (0x100000 | (mul << 8) | div)
+
+#define NFORCE2_MIN_FSB 50
+#define NFORCE2_SAFE_DISTANCE 50
+
+/* Delay in ms between FSB changes */
+/* #define NFORCE2_DELAY 10 */
+
+/*
+ * nforce2_chipset:
+ * FSB is changed using the chipset
+ */
+static struct pci_dev *nforce2_dev;
+
+/* fid:
+ * multiplier * 10
+ */
+static int fid;
+
+/* min_fsb, max_fsb:
+ * minimum and maximum FSB (= FSB at boot time)
+ */
+static int min_fsb;
+static int max_fsb;
+
+MODULE_AUTHOR("Sebastian Witt <se.witt@gmx.net>");
+MODULE_DESCRIPTION("nForce2 FSB changing cpufreq driver");
+MODULE_LICENSE("GPL");
+
+module_param(fid, int, 0444);
+module_param(min_fsb, int, 0444);
+
+MODULE_PARM_DESC(fid, "CPU multiplier to use (11.5 = 115)");
+MODULE_PARM_DESC(min_fsb,
+		"Minimum FSB to use, if not defined: current FSB - 50");
+
+/**
+ * nforce2_calc_fsb - calculate FSB
+ * @pll: PLL value
+ *
+ *   Calculates FSB from PLL value
+ */
+static int nforce2_calc_fsb(int pll)
+{
+	unsigned char mul, div;
+
+	mul = (pll >> 8) & 0xff;
+	div = pll & 0xff;
+
+	if (div > 0)
+		return NFORCE2_XTAL * mul / div;
+
+	return 0;
+}
+
+/**
+ * nforce2_calc_pll - calculate PLL value
+ * @fsb: FSB
+ *
+ *   Calculate PLL value for given FSB
+ */
+static int nforce2_calc_pll(unsigned int fsb)
+{
+	unsigned char xmul, xdiv;
+	unsigned char mul = 0, div = 0;
+	int tried = 0;
+
+	/* Try to calculate multiplier and divider up to 4 times */
+	while (((mul == 0) || (div == 0)) && (tried <= 3)) {
+		for (xdiv = 2; xdiv <= 0x80; xdiv++)
+			for (xmul = 1; xmul <= 0xfe; xmul++)
+				if (nforce2_calc_fsb(NFORCE2_PLL(xmul, xdiv)) ==
+				    fsb + tried) {
+					mul = xmul;
+					div = xdiv;
+				}
+		tried++;
+	}
+
+	if ((mul == 0) || (div == 0))
+		return -1;
+
+	return NFORCE2_PLL(mul, div);
+}
+
+/**
+ * nforce2_write_pll - write PLL value to chipset
+ * @pll: PLL value
+ *
+ *   Writes new FSB PLL value to chipset
+ */
+static void nforce2_write_pll(int pll)
+{
+	int temp;
+
+	/* Set the pll addr. to 0x00 */
+	pci_write_config_dword(nforce2_dev, NFORCE2_PLLADR, 0);
+
+	/* Now write the value in all 64 registers */
+	for (temp = 0; temp <= 0x3f; temp++)
+		pci_write_config_dword(nforce2_dev, NFORCE2_PLLREG, pll);
+}
+
+/**
+ * nforce2_fsb_read - Read FSB
+ *
+ *   Read FSB from chipset
+ *   If bootfsb != 0, return FSB at boot-time
+ */
+static unsigned int nforce2_fsb_read(int bootfsb)
+{
+	struct pci_dev *nforce2_sub5;
+	u32 fsb, temp = 0;
+
+	/* Get chipset boot FSB from subdevice 5 (FSB at boot-time) */
+	nforce2_sub5 = pci_get_subsys(PCI_VENDOR_ID_NVIDIA, 0x01EF,
+				PCI_ANY_ID, PCI_ANY_ID, NULL);
+	if (!nforce2_sub5)
+		return 0;
+
+	pci_read_config_dword(nforce2_sub5, NFORCE2_BOOTFSB, &fsb);
+	fsb /= 1000000;
+
+	/* Check if PLL register is already set */
+	pci_read_config_byte(nforce2_dev, NFORCE2_PLLENABLE, (u8 *)&temp);
+
+	if (bootfsb || !temp)
+		return fsb;
+
+	/* Use PLL register FSB value */
+	pci_read_config_dword(nforce2_dev, NFORCE2_PLLREG, &temp);
+	fsb = nforce2_calc_fsb(temp);
+
+	return fsb;
+}
+
+/**
+ * nforce2_set_fsb - set new FSB
+ * @fsb: New FSB
+ *
+ *   Sets new FSB
+ */
+static int nforce2_set_fsb(unsigned int fsb)
+{
+	u32 temp = 0;
+	unsigned int tfsb;
+	int diff;
+	int pll = 0;
+
+	if ((fsb > max_fsb) || (fsb < NFORCE2_MIN_FSB)) {
+		pr_err("FSB %d is out of range!\n", fsb);
+		return -EINVAL;
+	}
+
+	tfsb = nforce2_fsb_read(0);
+	if (!tfsb) {
+		pr_err("Error while reading the FSB\n");
+		return -EINVAL;
+	}
+
+	/* First write? Then set actual value */
+	pci_read_config_byte(nforce2_dev, NFORCE2_PLLENABLE, (u8 *)&temp);
+	if (!temp) {
+		pll = nforce2_calc_pll(tfsb);
+
+		if (pll < 0)
+			return -EINVAL;
+
+		nforce2_write_pll(pll);
+	}
+
+	/* Enable write access */
+	temp = 0x01;
+	pci_write_config_byte(nforce2_dev, NFORCE2_PLLENABLE, (u8)temp);
+
+	diff = tfsb - fsb;
+
+	if (!diff)
+		return 0;
+
+	while ((tfsb != fsb) && (tfsb <= max_fsb) && (tfsb >= min_fsb)) {
+		if (diff < 0)
+			tfsb++;
+		else
+			tfsb--;
+
+		/* Calculate the PLL reg. value */
+		pll = nforce2_calc_pll(tfsb);
+		if (pll == -1)
+			return -EINVAL;
+
+		nforce2_write_pll(pll);
+#ifdef NFORCE2_DELAY
+		mdelay(NFORCE2_DELAY);
+#endif
+	}
+
+	temp = 0x40;
+	pci_write_config_byte(nforce2_dev, NFORCE2_PLLADR, (u8)temp);
+
+	return 0;
+}
+
+/**
+ * nforce2_get - get the CPU frequency
+ * @cpu: CPU number
+ *
+ * Returns the CPU frequency
+ */
+static unsigned int nforce2_get(unsigned int cpu)
+{
+	if (cpu)
+		return 0;
+	return nforce2_fsb_read(0) * fid * 100;
+}
+
+/**
+ * nforce2_target - set a new CPUFreq policy
+ * @policy: new policy
+ * @target_freq: the target frequency
+ * @relation: how that frequency relates to achieved frequency
+ *  (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
+ *
+ * Sets a new CPUFreq policy.
+ */
+static int nforce2_target(struct cpufreq_policy *policy,
+			  unsigned int target_freq, unsigned int relation)
+{
+/*        unsigned long         flags; */
+	struct cpufreq_freqs freqs;
+	unsigned int target_fsb;
+
+	if ((target_freq > policy->max) || (target_freq < policy->min))
+		return -EINVAL;
+
+	target_fsb = target_freq / (fid * 100);
+
+	freqs.old = nforce2_get(policy->cpu);
+	freqs.new = target_fsb * fid * 100;
+
+	if (freqs.old == freqs.new)
+		return 0;
+
+	pr_debug("Old CPU frequency %d kHz, new %d kHz\n",
+	       freqs.old, freqs.new);
+
+	cpufreq_freq_transition_begin(policy, &freqs);
+
+	/* Disable IRQs */
+	/* local_irq_save(flags); */
+
+	if (nforce2_set_fsb(target_fsb) < 0)
+		pr_err("Changing FSB to %d failed\n", target_fsb);
+	else
+		pr_debug("Changed FSB successfully to %d\n",
+			target_fsb);
+
+	/* Enable IRQs */
+	/* local_irq_restore(flags); */
+
+	cpufreq_freq_transition_end(policy, &freqs, 0);
+
+	return 0;
+}
+
+/**
+ * nforce2_verify - verifies a new CPUFreq policy
+ * @policy: new policy
+ */
+static int nforce2_verify(struct cpufreq_policy_data *policy)
+{
+	unsigned int fsb_pol_max;
+
+	fsb_pol_max = policy->max / (fid * 100);
+
+	if (policy->min < (fsb_pol_max * fid * 100))
+		policy->max = (fsb_pol_max + 1) * fid * 100;
+
+	cpufreq_verify_within_cpu_limits(policy);
+	return 0;
+}
+
+static int nforce2_cpu_init(struct cpufreq_policy *policy)
+{
+	unsigned int fsb;
+	unsigned int rfid;
+
+	/* capability check */
+	if (policy->cpu != 0)
+		return -ENODEV;
+
+	/* Get current FSB */
+	fsb = nforce2_fsb_read(0);
+
+	if (!fsb)
+		return -EIO;
+
+	/* FIX: Get FID from CPU */
+	if (!fid) {
+		if (!cpu_khz) {
+			pr_warn("cpu_khz not set, can't calculate multiplier!\n");
+			return -ENODEV;
+		}
+
+		fid = cpu_khz / (fsb * 100);
+		rfid = fid % 5;
+
+		if (rfid) {
+			if (rfid > 2)
+				fid += 5 - rfid;
+			else
+				fid -= rfid;
+		}
+	}
+
+	pr_info("FSB currently at %i MHz, FID %d.%d\n",
+		fsb, fid / 10, fid % 10);
+
+	/* Set maximum FSB to FSB at boot time */
+	max_fsb = nforce2_fsb_read(1);
+
+	if (!max_fsb)
+		return -EIO;
+
+	if (!min_fsb)
+		min_fsb = max_fsb - NFORCE2_SAFE_DISTANCE;
+
+	if (min_fsb < NFORCE2_MIN_FSB)
+		min_fsb = NFORCE2_MIN_FSB;
+
+	/* cpuinfo and default policy values */
+	policy->min = policy->cpuinfo.min_freq = min_fsb * fid * 100;
+	policy->max = policy->cpuinfo.max_freq = max_fsb * fid * 100;
+
+	return 0;
+}
+
+static int nforce2_cpu_exit(struct cpufreq_policy *policy)
+{
+	return 0;
+}
+
+static struct cpufreq_driver nforce2_driver = {
+	.name = "nforce2",
+	.flags = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
+	.verify = nforce2_verify,
+	.target = nforce2_target,
+	.get = nforce2_get,
+	.init = nforce2_cpu_init,
+	.exit = nforce2_cpu_exit,
+};
+
+#ifdef MODULE
+static const struct pci_device_id nforce2_ids[] = {
+	{ PCI_VENDOR_ID_NVIDIA, PCI_DEVICE_ID_NVIDIA_NFORCE2 },
+	{}
+};
+MODULE_DEVICE_TABLE(pci, nforce2_ids);
+#endif
+
+/**
+ * nforce2_detect_chipset - detect the Southbridge which contains FSB PLL logic
+ *
+ * Detects nForce2 A2 and C1 stepping
+ *
+ */
+static int nforce2_detect_chipset(void)
+{
+	nforce2_dev = pci_get_subsys(PCI_VENDOR_ID_NVIDIA,
+					PCI_DEVICE_ID_NVIDIA_NFORCE2,
+					PCI_ANY_ID, PCI_ANY_ID, NULL);
+
+	if (nforce2_dev == NULL)
+		return -ENODEV;
+
+	pr_info("Detected nForce2 chipset revision %X\n",
+		nforce2_dev->revision);
+	pr_info("FSB changing is maybe unstable and can lead to crashes and data loss\n");
+
+	return 0;
+}
+
+/**
+ * nforce2_init - initializes the nForce2 CPUFreq driver
+ *
+ * Initializes the nForce2 FSB support. Returns -ENODEV on unsupported
+ * devices, -EINVAL on problems during initialization, and zero on
+ * success.
+ */
+static int __init nforce2_init(void)
+{
+	/* TODO: do we need to detect the processor? */
+
+	/* detect chipset */
+	if (nforce2_detect_chipset()) {
+		pr_info("No nForce2 chipset\n");
+		return -ENODEV;
+	}
+
+	return cpufreq_register_driver(&nforce2_driver);
+}
+
+/**
+ * nforce2_exit - unregisters cpufreq module
+ *
+ *   Unregisters nForce2 FSB change support.
+ */
+static void __exit nforce2_exit(void)
+{
+	cpufreq_unregister_driver(&nforce2_driver);
+}
+
+module_init(nforce2_init);
+module_exit(nforce2_exit);