diff options
Diffstat (limited to 'drivers/char/hw_random/n2-drv.c')
| -rw-r--r-- | drivers/char/hw_random/n2-drv.c | 771 |
1 files changed, 771 insertions, 0 deletions
diff --git a/drivers/char/hw_random/n2-drv.c b/drivers/char/hw_random/n2-drv.c new file mode 100644 index 000000000000..5220f541df25 --- /dev/null +++ b/drivers/char/hw_random/n2-drv.c @@ -0,0 +1,771 @@ +/* n2-drv.c: Niagara-2 RNG driver. + * + * Copyright (C) 2008 David S. Miller <davem@davemloft.net> + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/workqueue.h> +#include <linux/preempt.h> +#include <linux/hw_random.h> + +#include <linux/of.h> +#include <linux/of_device.h> + +#include <asm/hypervisor.h> + +#include "n2rng.h" + +#define DRV_MODULE_NAME "n2rng" +#define PFX DRV_MODULE_NAME ": " +#define DRV_MODULE_VERSION "0.1" +#define DRV_MODULE_RELDATE "May 15, 2008" + +static char version[] __devinitdata = + DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")\n"; + +MODULE_AUTHOR("David S. Miller (davem@davemloft.net)"); +MODULE_DESCRIPTION("Niagara2 RNG driver"); +MODULE_LICENSE("GPL"); +MODULE_VERSION(DRV_MODULE_VERSION); + +/* The Niagara2 RNG provides a 64-bit read-only random number + * register, plus a control register. Access to the RNG is + * virtualized through the hypervisor so that both guests and control + * nodes can access the device. + * + * The entropy source consists of raw entropy sources, each + * constructed from a voltage controlled oscillator whose phase is + * jittered by thermal noise sources. + * + * The oscillator in each of the three raw entropy sources run at + * different frequencies. Normally, all three generator outputs are + * gathered, xored together, and fed into a CRC circuit, the output of + * which is the 64-bit read-only register. + * + * Some time is necessary for all the necessary entropy to build up + * such that a full 64-bits of entropy are available in the register. + * In normal operating mode (RNG_CTL_LFSR is set), the chip implements + * an interlock which blocks register reads until sufficient entropy + * is available. + * + * A control register is provided for adjusting various aspects of RNG + * operation, and to enable diagnostic modes. Each of the three raw + * entropy sources has an enable bit (RNG_CTL_ES{1,2,3}). Also + * provided are fields for controlling the minimum time in cycles + * between read accesses to the register (RNG_CTL_WAIT, this controls + * the interlock described in the previous paragraph). + * + * The standard setting is to have the mode bit (RNG_CTL_LFSR) set, + * all three entropy sources enabled, and the interlock time set + * appropriately. + * + * The CRC polynomial used by the chip is: + * + * P(X) = x64 + x61 + x57 + x56 + x52 + x51 + x50 + x48 + x47 + x46 + + * x43 + x42 + x41 + x39 + x38 + x37 + x35 + x32 + x28 + x25 + + * x22 + x21 + x17 + x15 + x13 + x12 + x11 + x7 + x5 + x + 1 + * + * The RNG_CTL_VCO value of each noise cell must be programmed + * seperately. This is why 4 control register values must be provided + * to the hypervisor. During a write, the hypervisor writes them all, + * one at a time, to the actual RNG_CTL register. The first three + * values are used to setup the desired RNG_CTL_VCO for each entropy + * source, for example: + * + * control 0: (1 << RNG_CTL_VCO_SHIFT) | RNG_CTL_ES1 + * control 1: (2 << RNG_CTL_VCO_SHIFT) | RNG_CTL_ES2 + * control 2: (3 << RNG_CTL_VCO_SHIFT) | RNG_CTL_ES3 + * + * And then the fourth value sets the final chip state and enables + * desired. + */ + +static int n2rng_hv_err_trans(unsigned long hv_err) +{ + switch (hv_err) { + case HV_EOK: + return 0; + case HV_EWOULDBLOCK: + return -EAGAIN; + case HV_ENOACCESS: + return -EPERM; + case HV_EIO: + return -EIO; + case HV_EBUSY: + return -EBUSY; + case HV_EBADALIGN: + case HV_ENORADDR: + return -EFAULT; + default: + return -EINVAL; + } +} + +static unsigned long n2rng_generic_read_control_v2(unsigned long ra, + unsigned long unit) +{ + unsigned long hv_err, state, ticks, watchdog_delta, watchdog_status; + int block = 0, busy = 0; + + while (1) { + hv_err = sun4v_rng_ctl_read_v2(ra, unit, &state, + &ticks, + &watchdog_delta, + &watchdog_status); + if (hv_err == HV_EOK) + break; + + if (hv_err == HV_EBUSY) { + if (++busy >= N2RNG_BUSY_LIMIT) + break; + + udelay(1); + } else if (hv_err == HV_EWOULDBLOCK) { + if (++block >= N2RNG_BLOCK_LIMIT) + break; + + __delay(ticks); + } else + break; + } + + return hv_err; +} + +/* In multi-socket situations, the hypervisor might need to + * queue up the RNG control register write if it's for a unit + * that is on a cpu socket other than the one we are executing on. + * + * We poll here waiting for a successful read of that control + * register to make sure the write has been actually performed. + */ +static unsigned long n2rng_control_settle_v2(struct n2rng *np, int unit) +{ + unsigned long ra = __pa(&np->scratch_control[0]); + + return n2rng_generic_read_control_v2(ra, unit); +} + +static unsigned long n2rng_write_ctl_one(struct n2rng *np, int unit, + unsigned long state, + unsigned long control_ra, + unsigned long watchdog_timeout, + unsigned long *ticks) +{ + unsigned long hv_err; + + if (np->hvapi_major == 1) { + hv_err = sun4v_rng_ctl_write_v1(control_ra, state, + watchdog_timeout, ticks); + } else { + hv_err = sun4v_rng_ctl_write_v2(control_ra, state, + watchdog_timeout, unit); + if (hv_err == HV_EOK) + hv_err = n2rng_control_settle_v2(np, unit); + *ticks = N2RNG_ACCUM_CYCLES_DEFAULT; + } + + return hv_err; +} + +static int n2rng_generic_read_data(unsigned long data_ra) +{ + unsigned long ticks, hv_err; + int block = 0, hcheck = 0; + + while (1) { + hv_err = sun4v_rng_data_read(data_ra, &ticks); + if (hv_err == HV_EOK) + return 0; + + if (hv_err == HV_EWOULDBLOCK) { + if (++block >= N2RNG_BLOCK_LIMIT) + return -EWOULDBLOCK; + __delay(ticks); + } else if (hv_err == HV_ENOACCESS) { + return -EPERM; + } else if (hv_err == HV_EIO) { + if (++hcheck >= N2RNG_HCHECK_LIMIT) + return -EIO; + udelay(10000); + } else + return -ENODEV; + } +} + +static unsigned long n2rng_read_diag_data_one(struct n2rng *np, + unsigned long unit, + unsigned long data_ra, + unsigned long data_len, + unsigned long *ticks) +{ + unsigned long hv_err; + + if (np->hvapi_major == 1) { + hv_err = sun4v_rng_data_read_diag_v1(data_ra, data_len, ticks); + } else { + hv_err = sun4v_rng_data_read_diag_v2(data_ra, data_len, + unit, ticks); + if (!*ticks) + *ticks = N2RNG_ACCUM_CYCLES_DEFAULT; + } + return hv_err; +} + +static int n2rng_generic_read_diag_data(struct n2rng *np, + unsigned long unit, + unsigned long data_ra, + unsigned long data_len) +{ + unsigned long ticks, hv_err; + int block = 0; + + while (1) { + hv_err = n2rng_read_diag_data_one(np, unit, + data_ra, data_len, + &ticks); + if (hv_err == HV_EOK) + return 0; + + if (hv_err == HV_EWOULDBLOCK) { + if (++block >= N2RNG_BLOCK_LIMIT) + return -EWOULDBLOCK; + __delay(ticks); + } else if (hv_err == HV_ENOACCESS) { + return -EPERM; + } else if (hv_err == HV_EIO) { + return -EIO; + } else + return -ENODEV; + } +} + + +static int n2rng_generic_write_control(struct n2rng *np, + unsigned long control_ra, + unsigned long unit, + unsigned long state) +{ + unsigned long hv_err, ticks; + int block = 0, busy = 0; + + while (1) { + hv_err = n2rng_write_ctl_one(np, unit, state, control_ra, + np->wd_timeo, &ticks); + if (hv_err == HV_EOK) + return 0; + + if (hv_err == HV_EWOULDBLOCK) { + if (++block >= N2RNG_BLOCK_LIMIT) + return -EWOULDBLOCK; + __delay(ticks); + } else if (hv_err == HV_EBUSY) { + if (++busy >= N2RNG_BUSY_LIMIT) + return -EBUSY; + udelay(1); + } else + return -ENODEV; + } +} + +/* Just try to see if we can successfully access the control register + * of the RNG on the domain on which we are currently executing. + */ +static int n2rng_try_read_ctl(struct n2rng *np) +{ + unsigned long hv_err; + unsigned long x; + + if (np->hvapi_major == 1) { + hv_err = sun4v_rng_get_diag_ctl(); + } else { + /* We purposefully give invalid arguments, HV_NOACCESS + * is higher priority than the errors we'd get from + * these other cases, and that's the error we are + * truly interested in. + */ + hv_err = sun4v_rng_ctl_read_v2(0UL, ~0UL, &x, &x, &x, &x); + switch (hv_err) { + case HV_EWOULDBLOCK: + case HV_ENOACCESS: + break; + default: + hv_err = HV_EOK; + break; + } + } + + return n2rng_hv_err_trans(hv_err); +} + +#define CONTROL_DEFAULT_BASE \ + ((2 << RNG_CTL_ASEL_SHIFT) | \ + (N2RNG_ACCUM_CYCLES_DEFAULT << RNG_CTL_WAIT_SHIFT) | \ + RNG_CTL_LFSR) + +#define CONTROL_DEFAULT_0 \ + (CONTROL_DEFAULT_BASE | \ + (1 << RNG_CTL_VCO_SHIFT) | \ + RNG_CTL_ES1) +#define CONTROL_DEFAULT_1 \ + (CONTROL_DEFAULT_BASE | \ + (2 << RNG_CTL_VCO_SHIFT) | \ + RNG_CTL_ES2) +#define CONTROL_DEFAULT_2 \ + (CONTROL_DEFAULT_BASE | \ + (3 << RNG_CTL_VCO_SHIFT) | \ + RNG_CTL_ES3) +#define CONTROL_DEFAULT_3 \ + (CONTROL_DEFAULT_BASE | \ + RNG_CTL_ES1 | RNG_CTL_ES2 | RNG_CTL_ES3) + +static void n2rng_control_swstate_init(struct n2rng *np) +{ + int i; + + np->flags |= N2RNG_FLAG_CONTROL; + + np->health_check_sec = N2RNG_HEALTH_CHECK_SEC_DEFAULT; + np->accum_cycles = N2RNG_ACCUM_CYCLES_DEFAULT; + np->wd_timeo = N2RNG_WD_TIMEO_DEFAULT; + + for (i = 0; i < np->num_units; i++) { + struct n2rng_unit *up = &np->units[i]; + + up->control[0] = CONTROL_DEFAULT_0; + up->control[1] = CONTROL_DEFAULT_1; + up->control[2] = CONTROL_DEFAULT_2; + up->control[3] = CONTROL_DEFAULT_3; + } + + np->hv_state = HV_RNG_STATE_UNCONFIGURED; +} + +static int n2rng_grab_diag_control(struct n2rng *np) +{ + int i, busy_count, err = -ENODEV; + + busy_count = 0; + for (i = 0; i < 100; i++) { + err = n2rng_try_read_ctl(np); + if (err != -EAGAIN) + break; + + if (++busy_count > 100) { + dev_err(&np->op->dev, + "Grab diag control timeout.\n"); + return -ENODEV; + } + + udelay(1); + } + + return err; +} + +static int n2rng_init_control(struct n2rng *np) +{ + int err = n2rng_grab_diag_control(np); + + /* Not in the control domain, that's OK we are only a consumer + * of the RNG data, we don't setup and program it. + */ + if (err == -EPERM) + return 0; + if (err) + return err; + + n2rng_control_swstate_init(np); + + return 0; +} + +static int n2rng_data_read(struct hwrng *rng, u32 *data) +{ + struct n2rng *np = (struct n2rng *) rng->priv; + unsigned long ra = __pa(&np->test_data); + int len; + + if (!(np->flags & N2RNG_FLAG_READY)) { + len = 0; + } else if (np->flags & N2RNG_FLAG_BUFFER_VALID) { + np->flags &= ~N2RNG_FLAG_BUFFER_VALID; + *data = np->buffer; + len = 4; + } else { + int err = n2rng_generic_read_data(ra); + if (!err) { + np->buffer = np->test_data >> 32; + *data = np->test_data & 0xffffffff; + len = 4; + } else { + dev_err(&np->op->dev, "RNG error, restesting\n"); + np->flags &= ~N2RNG_FLAG_READY; + if (!(np->flags & N2RNG_FLAG_SHUTDOWN)) + schedule_delayed_work(&np->work, 0); + len = 0; + } + } + + return len; +} + +/* On a guest node, just make sure we can read random data properly. + * If a control node reboots or reloads it's n2rng driver, this won't + * work during that time. So we have to keep probing until the device + * becomes usable. + */ +static int n2rng_guest_check(struct n2rng *np) +{ + unsigned long ra = __pa(&np->test_data); + + return n2rng_generic_read_data(ra); +} + +static int n2rng_entropy_diag_read(struct n2rng *np, unsigned long unit, + u64 *pre_control, u64 pre_state, + u64 *buffer, unsigned long buf_len, + u64 *post_control, u64 post_state) +{ + unsigned long post_ctl_ra = __pa(post_control); + unsigned long pre_ctl_ra = __pa(pre_control); + unsigned long buffer_ra = __pa(buffer); + int err; + + err = n2rng_generic_write_control(np, pre_ctl_ra, unit, pre_state); + if (err) + return err; + + err = n2rng_generic_read_diag_data(np, unit, + buffer_ra, buf_len); + + (void) n2rng_generic_write_control(np, post_ctl_ra, unit, + post_state); + + return err; +} + +static u64 advance_polynomial(u64 poly, u64 val, int count) +{ + int i; + + for (i = 0; i < count; i++) { + int highbit_set = ((s64)val < 0); + + val <<= 1; + if (highbit_set) + val ^= poly; + } + + return val; +} + +static int n2rng_test_buffer_find(struct n2rng *np, u64 val) +{ + int i, count = 0; + + /* Purposefully skip over the first word. */ + for (i = 1; i < SELFTEST_BUFFER_WORDS; i++) { + if (np->test_buffer[i] == val) + count++; + } + return count; +} + +static void n2rng_dump_test_buffer(struct n2rng *np) +{ + int i; + + for (i = 0; i < SELFTEST_BUFFER_WORDS; i++) + dev_err(&np->op->dev, "Test buffer slot %d [0x%016lx]\n", + i, np->test_buffer[i]); +} + +static int n2rng_check_selftest_buffer(struct n2rng *np, unsigned long unit) +{ + u64 val = SELFTEST_VAL; + int err, matches, limit; + + matches = 0; + for (limit = 0; limit < SELFTEST_LOOPS_MAX; limit++) { + matches += n2rng_test_buffer_find(np, val); + if (matches >= SELFTEST_MATCH_GOAL) + break; + val = advance_polynomial(SELFTEST_POLY, val, 1); + } + + err = 0; + if (limit >= SELFTEST_LOOPS_MAX) { + err = -ENODEV; + dev_err(&np->op->dev, "Selftest failed on unit %lu\n", unit); + n2rng_dump_test_buffer(np); + } else + dev_info(&np->op->dev, "Selftest passed on unit %lu\n", unit); + + return err; +} + +static int n2rng_control_selftest(struct n2rng *np, unsigned long unit) +{ + int err; + + np->test_control[0] = (0x2 << RNG_CTL_ASEL_SHIFT); + np->test_control[1] = (0x2 << RNG_CTL_ASEL_SHIFT); + np->test_control[2] = (0x2 << RNG_CTL_ASEL_SHIFT); + np->test_control[3] = ((0x2 << RNG_CTL_ASEL_SHIFT) | + RNG_CTL_LFSR | + ((SELFTEST_TICKS - 2) << RNG_CTL_WAIT_SHIFT)); + + + err = n2rng_entropy_diag_read(np, unit, np->test_control, + HV_RNG_STATE_HEALTHCHECK, + np->test_buffer, + sizeof(np->test_buffer), + &np->units[unit].control[0], + np->hv_state); + if (err) + return err; + + return n2rng_check_selftest_buffer(np, unit); +} + +static int n2rng_control_check(struct n2rng *np) +{ + int i; + + for (i = 0; i < np->num_units; i++) { + int err = n2rng_control_selftest(np, i); + if (err) + return err; + } + return 0; +} + +/* The sanity checks passed, install the final configuration into the + * chip, it's ready to use. + */ +static int n2rng_control_configure_units(struct n2rng *np) +{ + int unit, err; + + err = 0; + for (unit = 0; unit < np->num_units; unit++) { + struct n2rng_unit *up = &np->units[unit]; + unsigned long ctl_ra = __pa(&up->control[0]); + int esrc; + u64 base; + + base = ((np->accum_cycles << RNG_CTL_WAIT_SHIFT) | + (2 << RNG_CTL_ASEL_SHIFT) | + RNG_CTL_LFSR); + + /* XXX This isn't the best. We should fetch a bunch + * XXX of words using each entropy source combined XXX + * with each VCO setting, and see which combinations + * XXX give the best random data. + */ + for (esrc = 0; esrc < 3; esrc++) + up->control[esrc] = base | + (esrc << RNG_CTL_VCO_SHIFT) | + (RNG_CTL_ES1 << esrc); + + up->control[3] = base | + (RNG_CTL_ES1 | RNG_CTL_ES2 | RNG_CTL_ES3); + + err = n2rng_generic_write_control(np, ctl_ra, unit, + HV_RNG_STATE_CONFIGURED); + if (err) + break; + } + + return err; +} + +static void n2rng_work(struct work_struct *work) +{ + struct n2rng *np = container_of(work, struct n2rng, work.work); + int err = 0; + + if (!(np->flags & N2RNG_FLAG_CONTROL)) { + err = n2rng_guest_check(np); + } else { + preempt_disable(); + err = n2rng_control_check(np); + preempt_enable(); + + if (!err) + err = n2rng_control_configure_units(np); + } + + if (!err) { + np->flags |= N2RNG_FLAG_READY; + dev_info(&np->op->dev, "RNG ready\n"); + } + + if (err && !(np->flags & N2RNG_FLAG_SHUTDOWN)) + schedule_delayed_work(&np->work, HZ * 2); +} + +static void __devinit n2rng_driver_version(void) +{ + static int n2rng_version_printed; + + if (n2rng_version_printed++ == 0) + pr_info("%s", version); +} + +static int __devinit n2rng_probe(struct of_device *op, + const struct of_device_id *match) +{ + int victoria_falls = (match->data != NULL); + int err = -ENOMEM; + struct n2rng *np; + + n2rng_driver_version(); + + np = kzalloc(sizeof(*np), GFP_KERNEL); + if (!np) + goto out; + np->op = op; + + INIT_DELAYED_WORK(&np->work, n2rng_work); + + if (victoria_falls) + np->flags |= N2RNG_FLAG_VF; + + err = -ENODEV; + np->hvapi_major = 2; + if (sun4v_hvapi_register(HV_GRP_RNG, + np->hvapi_major, + &np->hvapi_minor)) { + np->hvapi_major = 1; + if (sun4v_hvapi_register(HV_GRP_RNG, + np->hvapi_major, + &np->hvapi_minor)) { + dev_err(&op->dev, "Cannot register suitable " + "HVAPI version.\n"); + goto out_free; + } + } + + if (np->flags & N2RNG_FLAG_VF) { + if (np->hvapi_major < 2) { + dev_err(&op->dev, "VF RNG requires HVAPI major " + "version 2 or later, got %lu\n", + np->hvapi_major); + goto out_hvapi_unregister; + } + np->num_units = of_getintprop_default(op->node, + "rng-#units", 0); + if (!np->num_units) { + dev_err(&op->dev, "VF RNG lacks rng-#units property\n"); + goto out_hvapi_unregister; + } + } else + np->num_units = 1; + + dev_info(&op->dev, "Registered RNG HVAPI major %lu minor %lu\n", + np->hvapi_major, np->hvapi_minor); + + np->units = kzalloc(sizeof(struct n2rng_unit) * np->num_units, + GFP_KERNEL); + err = -ENOMEM; + if (!np->units) + goto out_hvapi_unregister; + + err = n2rng_init_control(np); + if (err) + goto out_free_units; + + dev_info(&op->dev, "Found %s RNG, units: %d\n", + ((np->flags & N2RNG_FLAG_VF) ? + "Victoria Falls" : "Niagara2"), + np->num_units); + + np->hwrng.name = "n2rng"; + np->hwrng.data_read = n2rng_data_read; + np->hwrng.priv = (unsigned long) np; + + err = hwrng_register(&np->hwrng); + if (err) + goto out_free_units; + + dev_set_drvdata(&op->dev, np); + + schedule_delayed_work(&np->work, 0); + + return 0; + +out_free_units: + kfree(np->units); + np->units = NULL; + +out_hvapi_unregister: + sun4v_hvapi_unregister(HV_GRP_RNG); + +out_free: + kfree(np); +out: + return err; +} + +static int __devexit n2rng_remove(struct of_device *op) +{ + struct n2rng *np = dev_get_drvdata(&op->dev); + + np->flags |= N2RNG_FLAG_SHUTDOWN; + + cancel_delayed_work_sync(&np->work); + + hwrng_unregister(&np->hwrng); + + sun4v_hvapi_unregister(HV_GRP_RNG); + + kfree(np->units); + np->units = NULL; + + kfree(np); + + dev_set_drvdata(&op->dev, NULL); + + return 0; +} + +static struct of_device_id n2rng_match[] = { + { + .name = "random-number-generator", + .compatible = "SUNW,n2-rng", + }, + { + .name = "random-number-generator", + .compatible = "SUNW,vf-rng", + .data = (void *) 1, + }, + {}, +}; +MODULE_DEVICE_TABLE(of, n2rng_match); + +static struct of_platform_driver n2rng_driver = { + .name = "n2rng", + .match_table = n2rng_match, + .probe = n2rng_probe, + .remove = __devexit_p(n2rng_remove), +}; + +static int __init n2rng_init(void) +{ + return of_register_driver(&n2rng_driver, &of_bus_type); +} + +static void __exit n2rng_exit(void) +{ + of_unregister_driver(&n2rng_driver); +} + +module_init(n2rng_init); +module_exit(n2rng_exit); |