linux-kernel - [PATCH v2 13/13] ACPI: CPPC: Simplify PCC shared memory region handling

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Message-Id: <20250305-pcc_fixes_updates-v2-13-1b1822bc8746@arm.com>
Date: Wed, 05 Mar 2025 16:38:17 +0000
From: Sudeep Holla <sudeep.holla@....com>
To: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Sudeep Holla <sudeep.holla@....com>, 
 Jassi Brar <jassisinghbrar@...il.com>, Huisong Li <lihuisong@...wei.com>, 
 Adam Young <admiyo@...amperecomputing.com>, 
 Robbie King <robbiek@...ghtlabs.com>, 
 "Rafael J. Wysocki" <rafael@...nel.org>
Subject: [PATCH v2 13/13] ACPI: CPPC: Simplify PCC shared memory region
 handling

The PCC driver now handles mapping and unmapping of shared memory
areas as part of pcc_mbox_{request,free}_channel(). Without these before,
this ACPI CPPC driver did handling of those mappings like several
other PCC mailbox client drivers.

There were redundant operations, leading to unnecessary code. Maintaining
the consistency across these driver was harder due to scattered handling
of shmem.

Just use the mapped shmem and remove all redundant operations from this
driver.

Cc: Rafael J. Wysocki <rafael@...nel.org>
Acked-by: Rafael J. Wysocki <rafael@...nel.org>
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
---
 drivers/acpi/cppc_acpi.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index f193e713825ac24203ece5f94d6cf99dd4724ce4..d972157a79b6ade2f3738c90128e8692141b3ee5 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -47,7 +47,6 @@
 
 struct cppc_pcc_data {
 	struct pcc_mbox_chan *pcc_channel;
-	void __iomem *pcc_comm_addr;
 	bool pcc_channel_acquired;
 	unsigned int deadline_us;
 	unsigned int pcc_mpar, pcc_mrtt, pcc_nominal;
@@ -95,7 +94,7 @@ static DEFINE_PER_CPU(int, cpu_pcc_subspace_idx);
 static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
 
 /* pcc mapped address + header size + offset within PCC subspace */
-#define GET_PCC_VADDR(offs, pcc_ss_id) (pcc_data[pcc_ss_id]->pcc_comm_addr + \
+#define GET_PCC_VADDR(offs, pcc_ss_id) (pcc_data[pcc_ss_id]->pcc_channel->shmem + \
 						0x8 + (offs))
 
 /* Check if a CPC register is in PCC */
@@ -223,7 +222,7 @@ static int check_pcc_chan(int pcc_ss_id, bool chk_err_bit)
 	int ret, status;
 	struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
 	struct acpi_pcct_shared_memory __iomem *generic_comm_base =
-		pcc_ss_data->pcc_comm_addr;
+					pcc_ss_data->pcc_channel->shmem;
 
 	if (!pcc_ss_data->platform_owns_pcc)
 		return 0;
@@ -258,7 +257,7 @@ static int send_pcc_cmd(int pcc_ss_id, u16 cmd)
 	int ret = -EIO, i;
 	struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
 	struct acpi_pcct_shared_memory __iomem *generic_comm_base =
-		pcc_ss_data->pcc_comm_addr;
+					pcc_ss_data->pcc_channel->shmem;
 	unsigned int time_delta;
 
 	/*
@@ -571,15 +570,6 @@ static int register_pcc_channel(int pcc_ss_idx)
 		pcc_data[pcc_ss_idx]->pcc_mpar = pcc_chan->max_access_rate;
 		pcc_data[pcc_ss_idx]->pcc_nominal = pcc_chan->latency;
 
-		pcc_data[pcc_ss_idx]->pcc_comm_addr =
-			acpi_os_ioremap(pcc_chan->shmem_base_addr,
-					pcc_chan->shmem_size);
-		if (!pcc_data[pcc_ss_idx]->pcc_comm_addr) {
-			pr_err("Failed to ioremap PCC comm region mem for %d\n",
-			       pcc_ss_idx);
-			return -ENOMEM;
-		}
-
 		/* Set flag so that we don't come here for each CPU. */
 		pcc_data[pcc_ss_idx]->pcc_channel_acquired = true;
 	}

-- 
2.34.1