Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753460AbdI1NRL (ORCPT ); Thu, 28 Sep 2017 09:17:11 -0400 Received: from foss.arm.com ([217.140.101.70]:57092 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752438AbdI1NOb (ORCPT ); Thu, 28 Sep 2017 09:14:31 -0400 From: Sudeep Holla To: ALKML , LKML , DTML Cc: Sudeep Holla , Roy Franz , Harb Abdulhamid , Nishanth Menon , Arnd Bergmann , Loc Ho , Alexey Klimov , Ryan Harkin , Jassi Brar Subject: [PATCH v3 11/22] firmware: arm_scmi: add support for polling based SCMI transfers Date: Thu, 28 Sep 2017 14:11:35 +0100 Message-Id: <1506604306-20739-12-git-send-email-sudeep.holla@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1506604306-20739-1-git-send-email-sudeep.holla@arm.com> References: <1506604306-20739-1-git-send-email-sudeep.holla@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2807 Lines: 83 It would be useful to have options to perform some SCMI transfers atomically by polling for the completion flag instead of interrupt driven. The SCMI specification has option to disable the interrupt and poll for the completion flag in the shared memory. This patch adds support for polling based SCMI transfers using that option. This might be used for uninterrupted/atomic DVFS operations from the scheduler context. Cc: Arnd Bergmann Signed-off-by: Sudeep Holla --- drivers/firmware/arm_scmi/driver.c | 41 ++++++++++++++++++++++++++++++-------- 1 file changed, 33 insertions(+), 8 deletions(-) diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index a1abcf2049ca..e1abedf15cb0 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -26,6 +26,7 @@ */ #include +#include #include #include #include @@ -369,6 +370,20 @@ void scmi_one_xfer_put(const struct scmi_handle *handle, struct scmi_xfer *xfer) up(&minfo->sem_xfer_count); } +static bool +scmi_xfer_poll_done(const struct scmi_info *info, struct scmi_xfer *xfer) +{ + struct scmi_shared_mem *mem = info->tx_payload; + u16 xfer_id = MSG_XTRACT_TOKEN(le32_to_cpu(mem->msg_header)); + + if (xfer->hdr.seq != xfer_id) + return false; + + return le32_to_cpu(mem->channel_status) & + (SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR | + SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE); +} + /** * scmi_do_xfer() - Do one transfer * @@ -395,14 +410,24 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer) /* mbox_send_message returns non-negative value on success, so reset */ ret = 0; - /* And we wait for the response. */ - timeout = msecs_to_jiffies(info->desc->max_rx_timeout_ms); - if (!wait_for_completion_timeout(&xfer->done, timeout)) { - dev_err(dev, "mbox timed out in resp(caller: %pF)\n", - (void *)_RET_IP_); - ret = -ETIMEDOUT; - } else if (xfer->hdr.status) { - ret = scmi_to_linux_errno(xfer->hdr.status); + if (xfer->hdr.poll_completion) { + timeout = info->desc->max_rx_timeout_ms * 100; + while (!scmi_xfer_poll_done(info, xfer) && timeout--) + udelay(10); + if (timeout) + scmi_fetch_response(xfer, info->tx_payload); + else + ret = -ETIMEDOUT; + } else { + /* And we wait for the response. */ + timeout = msecs_to_jiffies(info->desc->max_rx_timeout_ms); + if (!wait_for_completion_timeout(&xfer->done, timeout)) { + dev_err(dev, "mbox timed out in resp(caller: %pF)\n", + (void *)_RET_IP_); + ret = -ETIMEDOUT; + } else if (xfer->hdr.status) { + ret = scmi_to_linux_errno(xfer->hdr.status); + } } /* * NOTE: we might prefer not to need the mailbox ticker to manage the -- 2.7.4