From 2eeb02b28579fc317504a691f3acb0b9bf94b42b Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@linaro.org>
Date: Mon, 15 May 2017 19:23:24 +0200
Subject: PCI: faraday: Add clock handling
Add some optional clock handling to the Faraday FTPCI100. We just get and
prepare+enable the clocks right now, if they exist. We can add more
elaborate clock handling later.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
[bhelgaas: folded in "Make clocks compulsory" fix from
http://lkml.kernel.org/r/20170621085730.28804-1-linus.walleij@linaro.org
Also folded in the clock max/cur speed fixes from
http://lkml.kernel.org/r/20170621162651.25315-1-linus.walleij@linaro.org]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/host/pci-ftpci100.c | 56 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)
(limited to 'drivers/pci/host')
diff --git a/drivers/pci/host/pci-ftpci100.c b/drivers/pci/host/pci-ftpci100.c
index e938eebcb180..5162dffc102b 100644
--- a/drivers/pci/host/pci-ftpci100.c
+++ b/drivers/pci/host/pci-ftpci100.c
@@ -25,6 +25,7 @@
#include <linux/irqchip/chained_irq.h>
#include <linux/bitops.h>
#include <linux/irq.h>
+#include <linux/clk.h>
/*
* Special configuration registers directly in the first few words
@@ -37,6 +38,7 @@
#define PCI_CONFIG 0x28 /* PCI configuration command register */
#define PCI_DATA 0x2C
+#define FARADAY_PCI_STATUS_CMD 0x04 /* Status and command */
#define FARADAY_PCI_PMC 0x40 /* Power management control */
#define FARADAY_PCI_PMCSR 0x44 /* Power management status */
#define FARADAY_PCI_CTRL1 0x48 /* Control register 1 */
@@ -45,6 +47,8 @@
#define FARADAY_PCI_MEM2_BASE_SIZE 0x54 /* Memory base and size #2 */
#define FARADAY_PCI_MEM3_BASE_SIZE 0x58 /* Memory base and size #3 */
+#define PCI_STATUS_66MHZ_CAPABLE BIT(21)
+
/* Bits 31..28 gives INTD..INTA status */
#define PCI_CTRL2_INTSTS_SHIFT 28
#define PCI_CTRL2_INTMASK_CMDERR BIT(27)
@@ -117,6 +121,7 @@ struct faraday_pci {
void __iomem *base;
struct irq_domain *irqdomain;
struct pci_bus *bus;
+ struct clk *bus_clk;
};
static int faraday_res_to_memcfg(resource_size_t mem_base,
@@ -444,6 +449,9 @@ static int faraday_pci_probe(struct platform_device *pdev)
struct resource *mem;
struct resource *io;
struct pci_host_bridge *host;
+ struct clk *clk;
+ unsigned char max_bus_speed = PCI_SPEED_33MHz;
+ unsigned char cur_bus_speed = PCI_SPEED_33MHz;
int ret;
u32 val;
LIST_HEAD(res);
@@ -462,6 +470,24 @@ static int faraday_pci_probe(struct platform_device *pdev)
host->sysdata = p;
p->dev = dev;
+ /* Retrieve and enable optional clocks */
+ clk = devm_clk_get(dev, "PCLK");
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+ ret = clk_prepare_enable(clk);
+ if (ret) {
+ dev_err(dev, "could not prepare PCLK\n");
+ return ret;
+ }
+ p->bus_clk = devm_clk_get(dev, "PCICLK");
+ if (IS_ERR(p->bus_clk))
+ return PTR_ERR(clk);
+ ret = clk_prepare_enable(p->bus_clk);
+ if (ret) {
+ dev_err(dev, "could not prepare PCICLK\n");
+ return ret;
+ }
+
regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
p->base = devm_ioremap_resource(dev, regs);
if (IS_ERR(p->base))
@@ -524,6 +550,34 @@ static int faraday_pci_probe(struct platform_device *pdev)
}
}
+ /* Check bus clock if we can gear up to 66 MHz */
+ if (!IS_ERR(p->bus_clk)) {
+ unsigned long rate;
+ u32 val;
+
+ faraday_raw_pci_read_config(p, 0, 0,
+ FARADAY_PCI_STATUS_CMD, 4, &val);
+ rate = clk_get_rate(p->bus_clk);
+
+ if ((rate == 33000000) && (val & PCI_STATUS_66MHZ_CAPABLE)) {
+ dev_info(dev, "33MHz bus is 66MHz capable\n");
+ max_bus_speed = PCI_SPEED_66MHz;
+ ret = clk_set_rate(p->bus_clk, 66000000);
+ if (ret)
+ dev_err(dev, "failed to set bus clock\n");
+ } else {
+ dev_info(dev, "33MHz only bus\n");
+ max_bus_speed = PCI_SPEED_33MHz;
+ }
+
+ /* Bumping the clock may fail so read back the rate */
+ rate = clk_get_rate(p->bus_clk);
+ if (rate == 33000000)
+ cur_bus_speed = PCI_SPEED_33MHz;
+ if (rate == 66000000)
+ cur_bus_speed = PCI_SPEED_66MHz;
+ }
+
ret = faraday_pci_parse_map_dma_ranges(p, dev->of_node);
if (ret)
return ret;
@@ -535,6 +589,8 @@ static int faraday_pci_probe(struct platform_device *pdev)
return ret;
}
p->bus = host->bus;
+ p->bus->max_bus_speed = max_bus_speed;
+ p->bus->cur_bus_speed = cur_bus_speed;
pci_bus_assign_resources(p->bus);
pci_bus_add_devices(p->bus);
--
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