staging: mt7621-pci: add quirks for 'E2' revision using 'soc_device_attribute'

Depending on revision of the chip, reset lines are inverted. Make code
more readable making use of 'soc_device_match' in driver probe function.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20191006181032.19112-1-sergio.paracuellos@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-pci/pci-mt7621.c

@@ -29,15 +29,14 @@
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
+#include <linux/sys_soc.h>
 #include <mt7621.h>
 #include <ralink_regs.h>
 
 #include "../../pci/pci.h"
 
 /* sysctl */
-#define MT7621_CHIP_REV_ID		0x0c
 #define MT7621_GPIO_MODE		0x60
-#define CHIP_REV_MT7621_E2		0x0101
 
 /* MediaTek specific configuration registers */
 #define PCIE_FTS_NUM			0x70c
@@ -126,6 +125,8 @@ struct mt7621_pcie_port {
  * @ports: pointer to PCIe port information
  * @perst: gpio reset
  * @rst: pointer to pcie reset
+ * @resets_inverted: depends on chip revision
+ * reset lines are inverted.
  */
 struct mt7621_pcie {
 	void __iomem *base;
@@ -140,6 +141,7 @@ struct mt7621_pcie {
 	struct list_head ports;
 	struct gpio_desc *perst;
 	struct reset_control *rst;
+	bool resets_inverted;
 };
 
 static inline u32 pcie_read(struct mt7621_pcie *pcie, u32 reg)
@@ -229,9 +231,9 @@ static inline void mt7621_pcie_port_clk_disable(struct mt7621_pcie_port *port)
 
 static inline void mt7621_control_assert(struct mt7621_pcie_port *port)
 {
-	u32 chip_rev_id = rt_sysc_r32(MT7621_CHIP_REV_ID);
+	struct mt7621_pcie *pcie = port->pcie;
 
-	if ((chip_rev_id & 0xFFFF) == CHIP_REV_MT7621_E2)
+	if (pcie->resets_inverted)
 		reset_control_assert(port->pcie_rst);
 	else
 		reset_control_deassert(port->pcie_rst);
@@ -239,9 +241,9 @@ static inline void mt7621_control_assert(struct mt7621_pcie_port *port)
 
 static inline void mt7621_control_deassert(struct mt7621_pcie_port *port)
 {
-	u32 chip_rev_id = rt_sysc_r32(MT7621_CHIP_REV_ID);
+	struct mt7621_pcie *pcie = port->pcie;
 
-	if ((chip_rev_id & 0xFFFF) == CHIP_REV_MT7621_E2)
+	if (pcie->resets_inverted)
 		reset_control_deassert(port->pcie_rst);
 	else
 		reset_control_assert(port->pcie_rst);
@@ -641,9 +643,14 @@ static int mt7621_pcie_register_host(struct pci_host_bridge *host,
 	return pci_host_probe(host);
 }
 
+static const struct soc_device_attribute mt7621_pci_quirks_match[] = {
+	{ .soc_id = "mt7621", .revision = "E2" }
+};
+
 static int mt7621_pci_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	const struct soc_device_attribute *attr;
 	struct mt7621_pcie *pcie;
 	struct pci_host_bridge *bridge;
 	int err;
@@ -661,6 +668,10 @@ static int mt7621_pci_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, pcie);
 	INIT_LIST_HEAD(&pcie->ports);
 
+	attr = soc_device_match(mt7621_pci_quirks_match);
+	if (attr)
+		pcie->resets_inverted = true;
+
 	err = mt7621_pcie_parse_dt(pcie);
 	if (err) {
 		dev_err(dev, "Parsing DT failed\n");