linux-kernel - [PATCH v6 10/12] PCI: Add T_PERST_CLK

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Message-Id: <20240102-j7200-pcie-s2r-v6-10-4656ef6e6d66@bootlin.com>
Date: Wed, 15 May 2024 12:01:11 +0200
From: Thomas Richard <thomas.richard@...tlin.com>
To: Linus Walleij <linus.walleij@...aro.org>, 
 Bartosz Golaszewski <brgl@...ev.pl>, Tony Lindgren <tony@...mide.com>, 
 Aaro Koskinen <aaro.koskinen@....fi>, 
 Janusz Krzysztofik <jmkrzyszt@...il.com>, Vignesh R <vigneshr@...com>, 
 Andi Shyti <andi.shyti@...nel.org>, Peter Rosin <peda@...ntia.se>, 
 Lorenzo Pieralisi <lpieralisi@...nel.org>, 
 Krzysztof Wilczyński <kw@...ux.com>, 
 Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>, 
 Siddharth Vadapalli <s-vadapalli@...com>
Cc: linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-omap@...r.kernel.org, linux-i2c@...r.kernel.org, 
 linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 gregory.clement@...tlin.com, theo.lebrun@...tlin.com, 
 thomas.petazzoni@...tlin.com, u-kumar1@...com, 
 Thomas Richard <thomas.richard@...tlin.com>
Subject: [PATCH v6 10/12] PCI: Add T_PERST_CLK_US macro

"Power Sequencing and Reset Signal Timings" table (section 2.9.2) in PCI
EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, REV. 5.1 indicates PERST#
should be deasserted after minimum of 100us once REFCLK is stable (symbol
T_PERST-CLK).

Add a macro so that PCIe controller drivers can use it.

Signed-off-by: Thomas Richard <thomas.richard@...tlin.com>
---
 drivers/pci/pci.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 17fed1846847..c47b1d3b5887 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -16,6 +16,9 @@
 /* Power stable to PERST# inactive from PCIe card Electromechanical Spec */
 #define PCIE_T_PVPERL_MS		100
 
+/* REFCLK stable before PERST# inactive from PCIe card Electromechanical Spec */
+#define PCIE_T_PERST_CLK_US		100
+
 /*
  * PCIe r6.0, sec 5.3.3.2.1 <PME Synchronization>
  * Recommends 1ms to 10ms timeout to check L2 ready.

-- 
2.39.2