--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Request power readings for resources in a computing environment via
+ * diag 0x324. diag 0x324 stores the power readings in the power information
+ * block (pib).
+ *
+ * Copyright IBM Corp. 2024
+ */
+
+#define pr_fmt(fmt) "diag324: " fmt
+#include <linux/fs.h>
+#include <linux/gfp.h>
+#include <linux/ioctl.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/timer.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/vmalloc.h>
+
+#include <asm/diag.h>
+#include <asm/sclp.h>
+#include <asm/timex.h>
+#include <uapi/asm/diag.h>
+#include "diag_ioctl.h"
+
+enum subcode {
+ DIAG324_SUBC_0 = 0,
+ DIAG324_SUBC_1 = 1,
+ DIAG324_SUBC_2 = 2,
+};
+
+enum retcode {
+ DIAG324_RET_SUCCESS = 0x0001,
+ DIAG324_RET_SUBC_NOTAVAIL = 0x0103,
+ DIAG324_RET_INSUFFICIENT_SIZE = 0x0104,
+ DIAG324_RET_READING_UNAVAILABLE = 0x0105,
+};
+
+union diag324_response {
+ u64 response;
+ struct {
+ u64 installed : 32;
+ u64 : 16;
+ u64 rc : 16;
+ } sc0;
+ struct {
+ u64 format : 16;
+ u64 : 16;
+ u64 pib_len : 16;
+ u64 rc : 16;
+ } sc1;
+ struct {
+ u64 : 48;
+ u64 rc : 16;
+ } sc2;
+};
+
+union diag324_request {
+ u64 request;
+ struct {
+ u64 : 32;
+ u64 allocated : 16;
+ u64 : 12;
+ u64 sc : 4;
+ } sc2;
+};
+
+struct pib {
+ u32 : 8;
+ u32 num : 8;
+ u32 len : 16;
+ u32 : 24;
+ u32 hlen : 8;
+ u64 : 64;
+ u64 intv;
+ u8 r[];
+} __packed;
+
+struct pibdata {
+ struct pib *pib;
+ ktime_t expire;
+ u64 sequence;
+ size_t len;
+ int rc;
+};
+
+static DEFINE_MUTEX(pibmutex);
+static struct pibdata pibdata;
+
+#define PIBWORK_DELAY (5 * NSEC_PER_SEC)
+
+static void pibwork_handler(struct work_struct *work);
+static DECLARE_DELAYED_WORK(pibwork, pibwork_handler);
+
+static unsigned long diag324(unsigned long subcode, void *addr)
+{
+ union register_pair rp = { .even = (unsigned long)addr };
+
+ diag_stat_inc(DIAG_STAT_X324);
+ asm volatile("diag %[rp],%[subcode],0x324\n"
+ : [rp] "+d" (rp.pair)
+ : [subcode] "d" (subcode)
+ : "memory");
+ return rp.odd;
+}
+
+static void pibwork_handler(struct work_struct *work)
+{
+ struct pibdata *data = &pibdata;
+ ktime_t timedout;
+
+ mutex_lock(&pibmutex);
+ timedout = ktime_add_ns(data->expire, PIBWORK_DELAY);
+ if (ktime_before(ktime_get(), timedout)) {
+ mod_delayed_work(system_wq, &pibwork, nsecs_to_jiffies(PIBWORK_DELAY));
+ goto out;
+ }
+ vfree(data->pib);
+ data->pib = NULL;
+out:
+ mutex_unlock(&pibmutex);
+}
+
+static void pib_update(struct pibdata *data)
+{
+ union diag324_request req = { .sc2.sc = DIAG324_SUBC_2, .sc2.allocated = data->len };
+ union diag324_response res;
+ int rc;
+
+ memset(data->pib, 0, data->len);
+ res.response = diag324(req.request, data->pib);
+ switch (res.sc2.rc) {
+ case DIAG324_RET_SUCCESS:
+ rc = 0;
+ break;
+ case DIAG324_RET_SUBC_NOTAVAIL:
+ rc = -ENOENT;
+ break;
+ case DIAG324_RET_INSUFFICIENT_SIZE:
+ rc = -EMSGSIZE;
+ break;
+ case DIAG324_RET_READING_UNAVAILABLE:
+ rc = -EBUSY;
+ break;
+ default:
+ rc = -EINVAL;
+ }
+ data->rc = rc;
+}
+
+long diag324_pibbuf(unsigned long arg)
+{
+ struct diag324_pib __user *udata = (struct diag324_pib __user *)arg;
+ struct pibdata *data = &pibdata;
+ static bool first = true;
+ u64 address;
+ int rc;
+
+ if (!data->len)
+ return -EOPNOTSUPP;
+ if (get_user(address, &udata->address))
+ return -EFAULT;
+ mutex_lock(&pibmutex);
+ rc = -ENOMEM;
+ if (!data->pib)
+ data->pib = vmalloc(data->len);
+ if (!data->pib)
+ goto out;
+ if (first || ktime_after(ktime_get(), data->expire)) {
+ pib_update(data);
+ data->sequence++;
+ data->expire = ktime_add_ns(ktime_get(), tod_to_ns(data->pib->intv));
+ mod_delayed_work(system_wq, &pibwork, nsecs_to_jiffies(PIBWORK_DELAY));
+ first = false;
+ }
+ rc = data->rc;
+ if (rc != 0 && rc != -EBUSY)
+ goto out;
+ rc = copy_to_user((void __user *)address, data->pib, data->pib->len);
+ rc |= put_user(data->sequence, &udata->sequence);
+ if (rc)
+ rc = -EFAULT;
+out:
+ mutex_unlock(&pibmutex);
+ return rc;
+}
+
+long diag324_piblen(unsigned long arg)
+{
+ struct pibdata *data = &pibdata;
+
+ if (!data->len)
+ return -EOPNOTSUPP;
+ if (put_user(data->len, (size_t __user *)arg))
+ return -EFAULT;
+ return 0;
+}
+
+static int __init diag324_init(void)
+{
+ union diag324_response res;
+ unsigned long installed;
+
+ if (!sclp.has_diag324)
+ return -EOPNOTSUPP;
+ res.response = diag324(DIAG324_SUBC_0, NULL);
+ if (res.sc0.rc != DIAG324_RET_SUCCESS)
+ return -EOPNOTSUPP;
+ installed = res.response;
+ if (!test_bit_inv(DIAG324_SUBC_1, &installed))
+ return -EOPNOTSUPP;
+ if (!test_bit_inv(DIAG324_SUBC_2, &installed))
+ return -EOPNOTSUPP;
+ res.response = diag324(DIAG324_SUBC_1, NULL);
+ if (res.sc1.rc != DIAG324_RET_SUCCESS)
+ return -EOPNOTSUPP;
+ pibdata.len = res.sc1.pib_len;
+ return 0;
+}
+device_initcall(diag324_init);
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