mvebu: armada-37xx: Backport PCI aardvark patches

This commit contains patches for PCI aardvark driver and relevant DTS
changes for Turris MOX and EspressoBin backported from mainline kernel.
It fixes support for old ATF, various wifi cards, mainly Compex WLE900VX.

Signed-off-by: Pali Rohár <pali@kernel.org>

1 files changed, 208 insertions, 0 deletions

diff --git a/target/linux/mvebu/patches-5.4/405-PCI-aardvark-Improve-link-training.patch b/target/linux/mvebu/patches-5.4/405-PCI-aardvark-Improve-link-training.patch
new file mode 100644
index 0000000000..20723894ec
--- /dev/null
+++ b/target/linux/mvebu/patches-5.4/405-PCI-aardvark-Improve-link-training.patch
@@ -0,0 +1,208 @@
+From 43fc679ced18006b12d918d7a8a4af392b7fbfe7 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Marek=20Beh=C3=BAn?= <marek.behun@nic.cz>
+Date: Thu, 30 Apr 2020 10:06:17 +0200
+Subject: [PATCH] PCI: aardvark: Improve link training
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Currently the aardvark driver trains link in PCIe gen2 mode. This may
+cause some buggy gen1 cards (such as Compex WLE900VX) to be unstable or
+even not detected. Moreover when ASPM code tries to retrain link second
+time, these cards may stop responding and link goes down. If gen1 is
+used this does not happen.
+
+Unconditionally forcing gen1 is not a good solution since it may have
+performance impact on gen2 cards.
+
+To overcome this, read 'max-link-speed' property (as defined in PCI
+device tree bindings) and use this as max gen mode. Then iteratively try
+link training at this mode or lower until successful. After successful
+link training choose final controller gen based on Negotiated Link Speed
+from Link Status register, which should match card speed.
+
+Link: https://lore.kernel.org/r/20200430080625.26070-5-pali@kernel.org
+Tested-by: Tomasz Maciej Nowak <tmn505@gmail.com>
+Signed-off-by: Pali Rohár <pali@kernel.org>
+Signed-off-by: Marek Behún <marek.behun@nic.cz>
+Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+Reviewed-by: Rob Herring <robh@kernel.org>
+Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
+---
+ drivers/pci/controller/pci-aardvark.c | 114 ++++++++++++++++++++------
+ 1 file changed, 89 insertions(+), 25 deletions(-)
+
+--- a/drivers/pci/controller/pci-aardvark.c
++++ b/drivers/pci/controller/pci-aardvark.c
+@@ -39,6 +39,7 @@
+ #define PCIE_CORE_LINK_CTRL_STAT_REG				0xd0
+ #define     PCIE_CORE_LINK_L0S_ENTRY				BIT(0)
+ #define     PCIE_CORE_LINK_TRAINING				BIT(5)
++#define     PCIE_CORE_LINK_SPEED_SHIFT				16
+ #define     PCIE_CORE_LINK_WIDTH_SHIFT				20
+ #define PCIE_CORE_ERR_CAPCTL_REG				0x118
+ #define     PCIE_CORE_ERR_CAPCTL_ECRC_CHK_TX			BIT(5)
+@@ -201,6 +202,7 @@ struct advk_pcie {
+ 	struct mutex msi_used_lock;
+ 	u16 msi_msg;
+ 	int root_bus_nr;
++	int link_gen;
+ 	struct pci_bridge_emul bridge;
+ };
+ 
+@@ -225,20 +227,16 @@ static int advk_pcie_link_up(struct advk
+ 
+ static int advk_pcie_wait_for_link(struct advk_pcie *pcie)
+ {
+-	struct device *dev = &pcie->pdev->dev;
+ 	int retries;
+ 
+ 	/* check if the link is up or not */
+ 	for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) {
+-		if (advk_pcie_link_up(pcie)) {
+-			dev_info(dev, "link up\n");
++		if (advk_pcie_link_up(pcie))
+ 			return 0;
+-		}
+ 
+ 		usleep_range(LINK_WAIT_USLEEP_MIN, LINK_WAIT_USLEEP_MAX);
+ 	}
+ 
+-	dev_err(dev, "link never came up\n");
+ 	return -ETIMEDOUT;
+ }
+ 
+@@ -253,6 +251,85 @@ static void advk_pcie_wait_for_retrain(s
+ 	}
+ }
+ 
++static int advk_pcie_train_at_gen(struct advk_pcie *pcie, int gen)
++{
++	int ret, neg_gen;
++	u32 reg;
++
++	/* Setup link speed */
++	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
++	reg &= ~PCIE_GEN_SEL_MSK;
++	if (gen == 3)
++		reg |= SPEED_GEN_3;
++	else if (gen == 2)
++		reg |= SPEED_GEN_2;
++	else
++		reg |= SPEED_GEN_1;
++	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
++
++	/*
++	 * Enable link training. This is not needed in every call to this
++	 * function, just once suffices, but it does not break anything either.
++	 */
++	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
++	reg |= LINK_TRAINING_EN;
++	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
++
++	/*
++	 * Start link training immediately after enabling it.
++	 * This solves problems for some buggy cards.
++	 */
++	reg = advk_readl(pcie, PCIE_CORE_LINK_CTRL_STAT_REG);
++	reg |= PCIE_CORE_LINK_TRAINING;
++	advk_writel(pcie, reg, PCIE_CORE_LINK_CTRL_STAT_REG);
++
++	ret = advk_pcie_wait_for_link(pcie);
++	if (ret)
++		return ret;
++
++	reg = advk_readl(pcie, PCIE_CORE_LINK_CTRL_STAT_REG);
++	neg_gen = (reg >> PCIE_CORE_LINK_SPEED_SHIFT) & 0xf;
++
++	return neg_gen;
++}
++
++static void advk_pcie_train_link(struct advk_pcie *pcie)
++{
++	struct device *dev = &pcie->pdev->dev;
++	int neg_gen = -1, gen;
++
++	/*
++	 * Try link training at link gen specified by device tree property
++	 * 'max-link-speed'. If this fails, iteratively train at lower gen.
++	 */
++	for (gen = pcie->link_gen; gen > 0; --gen) {
++		neg_gen = advk_pcie_train_at_gen(pcie, gen);
++		if (neg_gen > 0)
++			break;
++	}
++
++	if (neg_gen < 0)
++		goto err;
++
++	/*
++	 * After successful training if negotiated gen is lower than requested,
++	 * train again on negotiated gen. This solves some stability issues for
++	 * some buggy gen1 cards.
++	 */
++	if (neg_gen < gen) {
++		gen = neg_gen;
++		neg_gen = advk_pcie_train_at_gen(pcie, gen);
++	}
++
++	if (neg_gen == gen) {
++		dev_info(dev, "link up at gen %i\n", gen);
++		return;
++	}
++
++err:
++	dev_err(dev, "link never came up\n");
++}
++
+ static void advk_pcie_setup_hw(struct advk_pcie *pcie)
+ {
+ 	u32 reg;
+@@ -288,12 +365,6 @@ static void advk_pcie_setup_hw(struct ad
+ 		PCIE_CORE_CTRL2_TD_ENABLE;
+ 	advk_writel(pcie, reg, PCIE_CORE_CTRL2_REG);
+ 
+-	/* Set GEN2 */
+-	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
+-	reg &= ~PCIE_GEN_SEL_MSK;
+-	reg |= SPEED_GEN_2;
+-	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
+-
+ 	/* Set lane X1 */
+ 	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
+ 	reg &= ~LANE_CNT_MSK;
+@@ -341,20 +412,7 @@ static void advk_pcie_setup_hw(struct ad
+ 	 */
+ 	msleep(PCI_PM_D3COLD_WAIT);
+ 
+-	/* Enable link training */
+-	reg = advk_readl(pcie, PCIE_CORE_CTRL0_REG);
+-	reg |= LINK_TRAINING_EN;
+-	advk_writel(pcie, reg, PCIE_CORE_CTRL0_REG);
+-
+-	/*
+-	 * Start link training immediately after enabling it.
+-	 * This solves problems for some buggy cards.
+-	 */
+-	reg = advk_readl(pcie, PCIE_CORE_LINK_CTRL_STAT_REG);
+-	reg |= PCIE_CORE_LINK_TRAINING;
+-	advk_writel(pcie, reg, PCIE_CORE_LINK_CTRL_STAT_REG);
+-
+-	advk_pcie_wait_for_link(pcie);
++	advk_pcie_train_link(pcie);
+ 
+ 	reg = advk_readl(pcie, PCIE_CORE_CMD_STATUS_REG);
+ 	reg |= PCIE_CORE_CMD_MEM_ACCESS_EN |
+@@ -1036,6 +1094,12 @@ static int advk_pcie_probe(struct platfo
+ 		return ret;
+ 	}
+ 
++	ret = of_pci_get_max_link_speed(dev->of_node);
++	if (ret <= 0 || ret > 3)
++		pcie->link_gen = 3;
++	else
++		pcie->link_gen = ret;
++
+ 	advk_pcie_setup_hw(pcie);
+ 
+ 	advk_sw_pci_bridge_init(pcie);