[PATCH 3/3] ioc4: PCI bus speed detection
From: Brent Casavant
Date: Mon May 23 2005 - 20:06:50 EST
Several hardware features of SGI's IOC4 I/O controller chip require
timing-related driver calculations dependent upon the PCI bus speed.
This patch enables the core IOC4 driver code to detect the actual bus
speed and store a value that can later be used by the IOC4 subdrivers
as needed.
Signed-off-by: Brent Casavant <bcasavan@xxxxxxx>
Acked-by: Pat Gefre <pfg@xxxxxxx>
drivers/serial/ioc4_serial.c | 33 ++++++-----
drivers/sn/Kconfig | 2
drivers/sn/ioc4.c | 128 +++++++++++++++++++++++++++++++++++++++++++ include/linux/ioc4.h | 37 ++++++++++--
4 files changed, 178 insertions(+), 22 deletions(-)
Index: linux/drivers/serial/ioc4_serial.c
===================================================================
--- linux.orig/drivers/serial/ioc4_serial.c 2005-05-23 16:02:30.367381957 -0500
+++ linux/drivers/serial/ioc4_serial.c 2005-05-23 16:08:46.636576838 -0500
@@ -299,7 +299,6 @@
} ioc4_serial;
/* UART clock speed */
-#define IOC4_SER_XIN_CLK IOC4_SER_XIN_CLK_66
#define IOC4_SER_XIN_CLK_66 66666667
#define IOC4_SER_XIN_CLK_33 33333333
@@ -1012,21 +1011,20 @@
* ioc4_attach_local - Device initialization.
* Called at *_attach() time for each
* IOC4 with serial ports in the system.
- * @control: ioc4_control ptr
- * @pdev: PCI handle for this device
- * @soft: soft struct for this device
- * @ioc4: ioc4 mem space
- */
-static int inline ioc4_attach_local(struct pci_dev *pdev,
- struct ioc4_control *control,
- struct ioc4_soft *soft, void __iomem *ioc4_misc,
- void __iomem *ioc4_serial)
+ * @idd: Master module data for this IOC4
+ */
+static int inline ioc4_attach_local(struct ioc4_driver_data *idd)
{
struct ioc4_port *port;
struct ioc4_port *ports[IOC4_NUM_SERIAL_PORTS];
int port_number;
uint16_t ioc4_revid_min = 62;
uint16_t ioc4_revid;
+ struct pci_dev *pdev = idd->idd_pdev;
+ struct ioc4_control* control = idd->idd_serial_data;
+ struct ioc4_soft *soft = control->ic_soft;
+ void __iomem *ioc4_misc = idd->idd_misc_regs;
+ void __iomem *ioc4_serial = soft->is_ioc4_serial_addr;
/* IOC4 firmware must be at least rev 62 */
pci_read_config_word(pdev, PCI_COMMAND_SPECIAL, &ioc4_revid);
@@ -1063,7 +1061,15 @@
port->ip_ioc4_soft = soft;
port->ip_pdev = pdev;
port->ip_ienb = 0;
- port->ip_pci_bus_speed = IOC4_SER_XIN_CLK;
+ /* Use baud rate calculations based on detected PCI
+ * bus speed. Simply test whether the PCI clock is
+ * running closer to 66MHz or 33MHz.
+ */
+ if (idd->count_period/IOC4_EXTINT_COUNT_DIVISOR < 20) {
+ port->ip_pci_bus_speed = IOC4_SER_XIN_CLK_66;
+ } else {
+ port->ip_pci_bus_speed = IOC4_SER_XIN_CLK_33;
+ }
port->ip_baud = 9600;
port->ip_control = control;
port->ip_mem = ioc4_misc;
@@ -2733,9 +2739,8 @@
"%s : request_irq fails for IRQ 0x%x\n ",
__FUNCTION__, idd->idd_pdev->irq);
}
- if ((ret = ioc4_attach_local(idd->idd_pdev, control, soft,
- soft->is_ioc4_misc_addr,
- soft->is_ioc4_serial_addr)))
+ ret = ioc4_attach_local(idd);
+ if (ret)
goto out4;
/* register port with the serial core */
Index: linux/include/linux/ioc4.h
===================================================================
--- linux.orig/include/linux/ioc4.h 2005-05-23 16:02:30.373241266 -0500
+++ linux/include/linux/ioc4.h 2005-05-23 16:08:46.639506492 -0500
@@ -11,6 +11,14 @@
#include <linux/interrupt.h>
+/***************
+ * Definitions *
+ ***************/
+
+/* Miscellaneous values inherent to hardware */
+
+#define IOC4_EXTINT_COUNT_DIVISOR 520 /* PCI clocks per COUNT tick */
+
/***********************************
* Structures needed by subdrivers *
***********************************/
@@ -119,19 +127,34 @@
} gppr[8]; /* Generic PIO pins */
};
-/* One of these per IOC4
- *
- * The idd_serial_data field is present here, even though it's used
- * solely by the serial subdriver, because the main IOC4 module
- * properly owns pci_{get,set}_drvdata functionality. This field
- * allows that subdriver to stash its own drvdata somewhere.
- */
+/* Masks for GPCR DIR pins */
+#define IOC4_GPCR_DIR_0 0x01 /* External interrupt output */
+#define IOC4_GPCR_DIR_1 0x02 /* External interrupt input */
+#define IOC4_GPCR_DIR_2 0x04
+#define IOC4_GPCR_DIR_3 0x08 /* Keyboard/mouse presence */
+#define IOC4_GPCR_DIR_4 0x10 /* Ser. port 0 xcvr select (0=232, 1=422) */
+#define IOC4_GPCR_DIR_5 0x20 /* Ser. port 1 xcvr select (0=232, 1=422) */
+#define IOC4_GPCR_DIR_6 0x40 /* Ser. port 2 xcvr select (0=232, 1=422) */
+#define IOC4_GPCR_DIR_7 0x80 /* Ser. port 3 xcvr select (0=232, 1=422) */
+
+/* Masks for GPCR EDGE pins */
+#define IOC4_GPCR_EDGE_0 0x01
+#define IOC4_GPCR_EDGE_1 0x02 /* External interrupt input */
+#define IOC4_GPCR_EDGE_2 0x04
+#define IOC4_GPCR_EDGE_3 0x08
+#define IOC4_GPCR_EDGE_4 0x10
+#define IOC4_GPCR_EDGE_5 0x20
+#define IOC4_GPCR_EDGE_6 0x40
+#define IOC4_GPCR_EDGE_7 0x80
+
+/* One of these per IOC4 */
struct ioc4_driver_data {
struct list_head idd_list;
unsigned long idd_bar0;
struct pci_dev *idd_pdev;
const struct pci_device_id *idd_pci_id;
struct __iomem ioc4_misc_regs *idd_misc_regs;
+ unsigned long count_period;
void *idd_serial_data;
};
Index: linux/drivers/sn/ioc4.c
===================================================================
--- linux.orig/drivers/sn/ioc4.c 2005-05-23 16:02:30.373241266 -0500
+++ linux/drivers/sn/ioc4.c 2005-05-23 16:21:12.165341514 -0500
@@ -29,7 +29,26 @@
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/ioc4.h>
+#include <linux/mmtimer.h>
+#include <linux/rtc.h>
#include <linux/rwsem.h>
+#include <asm/sn/addrs.h>
+#include <asm/sn/clksupport.h>
+#include <asm/sn/shub_mmr.h>
+
+/***************
+ * Definitions *
+ ***************/
+
+/* Tweakable values */
+
+/* PCI bus speed detection/calibration */
+#define IOC4_CALIBRATE_COUNT 63 /* Calibration cycle period */
+#define IOC4_CALIBRATE_CYCLES 256 /* Average over this many cycles */
+#define IOC4_CALIBRATE_DISCARD 2 /* Discard first few cycles */
+#define IOC4_CALIBRATE_LOW_MHZ 25 /* Lower bound on bus speed sanity */
+#define IOC4_CALIBRATE_HIGH_MHZ 75 /* Upper bound on bus speed sanity */
+#define IOC4_CALIBRATE_DEFAULT_MHZ 66 /* Assumed if sanity check fails */
/************************
* Submodule management *
@@ -101,6 +120,112 @@
* Device management *
*********************/
+#define IOC4_CALIBRATE_LOW_LIMIT \
+ (1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_LOW_MHZ)
+#define IOC4_CALIBRATE_HIGH_LIMIT \
+ (1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_HIGH_MHZ)
+#define IOC4_CALIBRATE_DEFAULT \
+ (1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_DEFAULT_MHZ)
+
+#define IOC4_CALIBRATE_END \
+ (IOC4_CALIBRATE_CYCLES + IOC4_CALIBRATE_DISCARD)
+
+#define IOC4_INT_OUT_MODE_TOGGLE 0x7 /* Toggle INT_OUT every COUNT+1 ticks */
+
+/* Determines external interrupt output clock period of the PCI bus an
+ * IOC4 is attached to. This value can be used to determine the PCI
+ * bus speed.
+ *
+ * IOC4 has a design feature that various internal timers are derived from
+ * the PCI bus clock. This causes IOC4 device drivers to need to take the
+ * bus speed into account when setting various register values (e.g. INT_OUT
+ * register COUNT field, UART divisors, etc). Since this information is
+ * needed by several subdrivers, it is determined by the main IOC4 driver,
+ * even though the following code utilizes external interrupt registers
+ * to perform the speed calculation.
+ */
+static void
+ioc4_clock_calibrate(struct ioc4_driver_data *idd)
+{
+ extern unsigned long sn_rtc_cycles_per_second;
+ union ioc4_int_out int_out;
+ union ioc4_gpcr gpcr;
+ unsigned int state, last_state = 1;
+ uint64_t start = 0, end, period;
+ unsigned int count = 0;
+
+ /* Enable output */
+ gpcr.raw = 0;
+ gpcr.fields.dir = IOC4_GPCR_DIR_0;
+ gpcr.fields.int_out_en = 1;
+ writel(gpcr.raw, &idd->idd_misc_regs->gpcr_s.raw);
+
+ /* Reset to power-on state */
+ writel(0, &idd->idd_misc_regs->int_out.raw);
+ mmiowb();
+
+ printk(KERN_INFO
+ "%s: Calibrating PCI bus speed "
+ "for pci_dev %s ... ", __FUNCTION__, pci_name(idd->idd_pdev));
+ /* Set up square wave */
+ int_out.raw = 0;
+ int_out.fields.count = IOC4_CALIBRATE_COUNT;
+ int_out.fields.mode = IOC4_INT_OUT_MODE_TOGGLE;
+ int_out.fields.diag = 0;
+ writel(int_out.raw, &idd->idd_misc_regs->int_out.raw);
+ mmiowb();
+
+ /* Check square wave period averaged over some number of cycles */
+ do {
+ int_out.raw = readl(&idd->idd_misc_regs->int_out.raw);
+ state = int_out.fields.int_out;
+ if (!last_state && state) {
+ count++;
+ if (count == IOC4_CALIBRATE_END) {
+ end = rtc_time();
+ break;
+ } else if (count == IOC4_CALIBRATE_DISCARD)
+ start = rtc_time();
+ }
+ last_state = state;
+ } while (1);
+
+ /* Calculation rearranged to preserve intermediate precision.
+ * Logically:
+ * 1. "end - start" gives us number of RTC cycles over all the
+ * square wave cycles measured.
+ * 2. Divide by number of square wave cycles to get number of
+ * RTC cycles per square wave cycle.
+ * 3. Divide by 2*(int_out.fields.count+1), which is the formula
+ * by which the IOC4 generates the square wave, to get the
+ * number of RTC cycles per IOC4 INT_OUT count.
+ * 4. Divide by sn_rtc_cycles_per_second to get seconds per
+ * count.
+ * 5. Multiply by 1E9 to get nanoseconds per count.
+ */
+ period = ((end - start) * 1000000000) /
+ (IOC4_CALIBRATE_CYCLES * 2 * (IOC4_CALIBRATE_COUNT + 1)
+ * sn_rtc_cycles_per_second);
+
+ /* Bounds check the result. */
+ if (period > IOC4_CALIBRATE_LOW_LIMIT ||
+ period < IOC4_CALIBRATE_HIGH_LIMIT) {
+ printk("failed. Assuming PCI clock ticks are %d ns.\n",
+ IOC4_CALIBRATE_DEFAULT / IOC4_EXTINT_COUNT_DIVISOR);
+ period = IOC4_CALIBRATE_DEFAULT;
+ } else {
+ printk("succeeded. PCI clock ticks are %ld ns.\n",
+ period / IOC4_EXTINT_COUNT_DIVISOR);
+ }
+
+ /* Remember results. We store the extint clock period rather
+ * than the PCI clock period so that greater precision is
+ * retained. Divide by IOC4_EXTINT_COUNT_DIVISOR to get
+ * PCI clock period.
+ */
+ idd->count_period = period;
+}
+
/* Adds a new instance of an IOC4 card */
static int
ioc4_probe(struct pci_dev *pdev, const struct pci_device_id *pci_id)
@@ -170,6 +295,9 @@
pci_write_config_dword(idd->idd_pdev, PCI_COMMAND,
pcmd | PCI_COMMAND_PARITY | PCI_COMMAND_SERR);
+ /* Determine PCI clock */
+ ioc4_clock_calibrate(idd);
+
/* Disable/clear all interrupts. Need to do this here lest
* one submodule request the shared IOC4 IRQ, but interrupt
* is generated by a different subdevice.
Index: linux/drivers/sn/Kconfig
===================================================================
--- linux.orig/drivers/sn/Kconfig 2005-05-23 16:03:49.698517875 -0500
+++ linux/drivers/sn/Kconfig 2005-05-23 16:08:46.643412698 -0500
@@ -6,7 +6,7 @@
config SGI_IOC4
tristate "SGI IOC4 Base IO support"
- depends on IA64_GENERIC || IA64_SGI_SN2
+ depends on (IA64_GENERIC || IA64_SGI_SN2) && MMTIMER
default m
---help---
This option enables basic support for the SGI IOC4-based Base IO
--
Brent Casavant If you had nothing to fear,
bcasavan@xxxxxxx how then could you be brave?
Silicon Graphics, Inc. -- Queen Dama, Source Wars
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