[PATCH 05/10] soc: fujitsu: hwb: Add IOC_BW_UNASSIGN ioctl

[Misono Tomohiro]

IOC_BW_UNASSIGN resets what IOC_BW_ASSIGN did on each PE.
This ioctl will also be called as many times as the number of PEs joining
synchronization.

Signed-off-by: Misono Tomohiro <misono.tomohiro at jp.fujitsu.com>
---
 drivers/soc/fujitsu/fujitsu_hwb.c      | 93 ++++++++++++++++++++++++++
 include/uapi/linux/fujitsu_hpc_ioctl.h |  2 +
 2 files changed, 95 insertions(+)

diff --git a/drivers/soc/fujitsu/fujitsu_hwb.c b/drivers/soc/fujitsu/fujitsu_hwb.c
index 85ffc1642dd9..8c4cabd60872 100644
--- a/drivers/soc/fujitsu/fujitsu_hwb.c
+++ b/drivers/soc/fujitsu/fujitsu_hwb.c
@@ -531,6 +531,96 @@ static int ioc_bw_assign(struct file *filp, void __user *argp)
 	return ret;
 }
 
+static int is_bw_unassignable(struct bb_info *bb_info, int cpu)
+{
+	u8 ppe;
+
+	if (!cpumask_test_and_clear_cpu(cpu, bb_info->assigned_pemask)) {
+		pr_err("This pe is not assigned: %u/%u/%d\n", bb_info->cmg, bb_info->bb, cpu);
+		return -EINVAL;
+	}
+
+	ppe = _hwinfo.core_map[cpu].ppe;
+	if (!test_bit(bb_info->bw[ppe], &_hwinfo.used_bw_bmap[cpu])) {
+		/* should not happen */
+		pr_crit("Logic error. This window is not assigned: %u/%u/%d\n",
+							bb_info->cmg, bb_info->bb, cpu);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void teardown_ctl_reg(struct bb_info *bb_info, int cpu)
+{
+	if (_hwinfo.used_bw_bmap[cpu] != 0)
+		/* Other window on this PE is still in use. Nothing todo */
+		return;
+
+	/*
+	 * This is the last unassign on this PE.
+	 * Clear all bits to disallow access to BST_SYNC/LBSY_SYNC from EL0
+	 */
+	write_sysreg_s(0, FHWB_CTRL_EL1);
+
+	pr_debug("Teardown ctl reg. cpu: %d\n", cpu);
+}
+
+static void teardown_bw(struct bb_info *bb_info, int cpu)
+{
+	u8 window;
+	u8 ppe;
+
+	/* Just clear all bits */
+	ppe = _hwinfo.core_map[cpu].ppe;
+	window = bb_info->bw[ppe];
+	write_bw_reg(window, 0);
+
+	/* Update bitmap info */
+	clear_bit(window, &_hwinfo.used_bw_bmap[cpu]);
+	bb_info->bw[ppe] = -1;
+
+	pr_debug("Teardown bw. cpu: %d, window: %u, BB: %u, bw_bmap: %lx, assigned_pemask: %*pbl\n",
+			cpu, window, bb_info->bb,
+			_hwinfo.used_bw_bmap[cpu], cpumask_pr_args(bb_info->assigned_pemask));
+}
+
+static int ioc_bw_unassign(struct file *filp, void __user *argp)
+{
+	struct hwb_private_data *pdata = (struct hwb_private_data *)filp->private_data;
+	struct fujitsu_hwb_ioc_bw_ctl bw_ctl;
+	struct bb_info *bb_info;
+	int cpu;
+	int ret;
+	u8 cmg;
+
+	if (!is_bound_only_one_pe())
+		return -EPERM;
+
+	if (copy_from_user(&bw_ctl, (struct fujitsu_hwb_ioc_bw_ctl __user *)argp,
+						sizeof(struct fujitsu_hwb_ioc_bw_ctl)))
+		return -EFAULT;
+
+	cpu = smp_processor_id();
+	cmg = _hwinfo.core_map[cpu].cmg;
+	bb_info = get_bb_info(pdata, cmg, bw_ctl.bb);
+	if (IS_ERR(bb_info))
+		return PTR_ERR(bb_info);
+
+	/* See comments in ioc_bw_assign() */
+	preempt_disable();
+	ret = is_bw_unassignable(bb_info, cpu);
+	if (!ret) {
+		teardown_bw(bb_info, cpu);
+		teardown_ctl_reg(bb_info, cpu);
+	}
+	preempt_enable();
+
+	put_bb_info(bb_info);
+
+	return ret;
+}
+
 static long fujitsu_hwb_dev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	void __user *argp = (void __user *)arg;
@@ -543,6 +633,9 @@ static long fujitsu_hwb_dev_ioctl(struct file *filp, unsigned int cmd, unsigned
 	case FUJITSU_HWB_IOC_BW_ASSIGN:
 		ret = ioc_bw_assign(filp, argp);
 		break;
+	case FUJITSU_HWB_IOC_BW_UNASSIGN:
+		ret = ioc_bw_unassign(filp, argp);
+		break;
 	default:
 		ret = -ENOTTY;
 		break;
diff --git a/include/uapi/linux/fujitsu_hpc_ioctl.h b/include/uapi/linux/fujitsu_hpc_ioctl.h
index ad90f8f3ae9a..396029f2bc0d 100644
--- a/include/uapi/linux/fujitsu_hpc_ioctl.h
+++ b/include/uapi/linux/fujitsu_hpc_ioctl.h
@@ -26,5 +26,7 @@ struct fujitsu_hwb_ioc_bw_ctl {
 	0x00, struct fujitsu_hwb_ioc_bb_ctl)
 #define FUJITSU_HWB_IOC_BW_ASSIGN _IOWR(__FUJITSU_IOCTL_MAGIC, \
 	0x01, struct fujitsu_hwb_ioc_bw_ctl)
+#define FUJITSU_HWB_IOC_BW_UNASSIGN _IOW(__FUJITSU_IOCTL_MAGIC, \
+	0x02, struct fujitsu_hwb_ioc_bw_ctl)
 
 #endif /* _UAPI_LINUX_FUJITSU_HPC_IOC_H */
-- 
2.26.2