From d4c477ca5448f19afaaf6c0cfd655009ea9e614d Mon Sep 17 00:00:00 2001 From: Brent Casavant Date: Tue, 21 Jun 2005 17:16:01 -0700 Subject: [PATCH] ioc4: PCI bus speed detection 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 Acked-by: Pat Gefre Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/serial/ioc4_serial.c | 31 ++++++----- drivers/sn/Kconfig | 2 +- drivers/sn/ioc4.c | 128 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 147 insertions(+), 14 deletions(-) (limited to 'drivers') diff --git a/drivers/serial/ioc4_serial.c b/drivers/serial/ioc4_serial.c index da5f10eb484..793c3a7cbe4 100644 --- a/drivers/serial/ioc4_serial.c +++ b/drivers/serial/ioc4_serial.c @@ -299,7 +299,6 @@ struct ioc4_serial { } 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 @@ static irqreturn_t ioc4_intr(int irq, void *arg, struct pt_regs *regs) * 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 + * @idd: Master module data for this IOC4 */ -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) +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 @@ static int inline ioc4_attach_local(struct pci_dev *pdev, 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 @@ ioc4_serial_attach_one(struct ioc4_driver_data *idd) "%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 */ diff --git a/drivers/sn/Kconfig b/drivers/sn/Kconfig index 20f7515ab83..13b8d249da5 100644 --- a/drivers/sn/Kconfig +++ b/drivers/sn/Kconfig @@ -6,7 +6,7 @@ menu "SN Devices" 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 diff --git a/drivers/sn/ioc4.c b/drivers/sn/ioc4.c index 70862d72ea9..ea75b3d0612 100644 --- a/drivers/sn/ioc4.c +++ b/drivers/sn/ioc4.c @@ -29,7 +29,26 @@ #include #include #include +#include +#include #include +#include +#include +#include + +/*************** + * 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 @@ ioc4_unregister_submodule(struct ioc4_submodule *is) * 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 @@ ioc4_probe(struct pci_dev *pdev, const struct pci_device_id *pci_id) 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. -- cgit v1.2.3