diff options
| -rw-r--r-- | drivers/bus/Kconfig | 15 | ||||
| -rw-r--r-- | drivers/bus/Makefile | 1 | ||||
| -rw-r--r-- | drivers/bus/bt1-apb.c | 422 |
3 files changed, 438 insertions, 0 deletions
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig index 1080dd26e268..030f0e59f193 100644 --- a/drivers/bus/Kconfig +++ b/drivers/bus/Kconfig @@ -29,6 +29,21 @@ config BRCMSTB_GISB_ARB arbiter. This driver provides timeout and target abort error handling and internal bus master decoding. +config BT1_APB + tristate "Baikal-T1 APB-bus driver" + depends on MIPS_BAIKAL_T1 || COMPILE_TEST + select REGMAP_MMIO + help + Baikal-T1 AXI-APB bridge is used to access the SoC subsystem CSRs. + IO requests are routed to this bus by means of the DW AMBA 3 AXI + Interconnect. In case of any APB protocol collisions, slave device + not responding on timeout an IRQ is raised with an erroneous address + reported to the APB terminator (APB Errors Handler Block). This + driver provides the interrupt handler to detect the erroneous + address, prints an error message about the address fault, updates an + errors counter. The counter and the APB-bus operations timeout can be + accessed via corresponding sysfs nodes. + config BT1_AXI tristate "Baikal-T1 AXI-bus driver" depends on MIPS_BAIKAL_T1 || COMPILE_TEST diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile index eaa25d171ebd..08ccbfaf7705 100644 --- a/drivers/bus/Makefile +++ b/drivers/bus/Makefile @@ -13,6 +13,7 @@ obj-$(CONFIG_MOXTET) += moxtet.o # DPAA2 fsl-mc bus obj-$(CONFIG_FSL_MC_BUS) += fsl-mc/ +obj-$(CONFIG_BT1_APB) += bt1-apb.o obj-$(CONFIG_BT1_AXI) += bt1-axi.o obj-$(CONFIG_IMX_WEIM) += imx-weim.o obj-$(CONFIG_MIPS_CDMM) += mips_cdmm.o diff --git a/drivers/bus/bt1-apb.c b/drivers/bus/bt1-apb.c new file mode 100644 index 000000000000..abccd1dfc544 --- /dev/null +++ b/drivers/bus/bt1-apb.c @@ -0,0 +1,422 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC + * + * Authors: + * Serge Semin <Sergey.Semin@baikalelectronics.ru> + * + * Baikal-T1 APB-bus driver + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/device.h> +#include <linux/atomic.h> +#include <linux/platform_device.h> +#include <linux/interrupt.h> +#include <linux/nmi.h> +#include <linux/of.h> +#include <linux/regmap.h> +#include <linux/clk.h> +#include <linux/reset.h> +#include <linux/time64.h> +#include <linux/clk.h> +#include <linux/sysfs.h> + +#define APB_EHB_ISR 0x00 +#define APB_EHB_ISR_PENDING BIT(0) +#define APB_EHB_ISR_MASK BIT(1) +#define APB_EHB_ADDR 0x04 +#define APB_EHB_TIMEOUT 0x08 + +#define APB_EHB_TIMEOUT_MIN 0x000003FFU +#define APB_EHB_TIMEOUT_MAX 0xFFFFFFFFU + +/* + * struct bt1_apb - Baikal-T1 APB EHB private data + * @dev: Pointer to the device structure. + * @regs: APB EHB registers map. + * @res: No-device error injection memory region. + * @irq: Errors IRQ number. + * @rate: APB-bus reference clock rate. + * @pclk: APB-reference clock. + * @prst: APB domain reset line. + * @count: Number of errors detected. + */ +struct bt1_apb { + struct device *dev; + + struct regmap *regs; + void __iomem *res; + int irq; + + unsigned long rate; + struct clk *pclk; + + struct reset_control *prst; + + atomic_t count; +}; + +static const struct regmap_config bt1_apb_regmap_cfg = { + .reg_bits = 32, + .val_bits = 32, + .reg_stride = 4, + .max_register = APB_EHB_TIMEOUT, + .fast_io = true +}; + +static inline unsigned long bt1_apb_n_to_timeout_us(struct bt1_apb *apb, u32 n) +{ + u64 timeout = (u64)n * USEC_PER_SEC; + + do_div(timeout, apb->rate); + + return timeout; + +} + +static inline unsigned long bt1_apb_timeout_to_n_us(struct bt1_apb *apb, + unsigned long timeout) +{ + u64 n = (u64)timeout * apb->rate; + + do_div(n, USEC_PER_SEC); + + return n; + +} + +static irqreturn_t bt1_apb_isr(int irq, void *data) +{ + struct bt1_apb *apb = data; + u32 addr = 0; + + regmap_read(apb->regs, APB_EHB_ADDR, &addr); + + dev_crit_ratelimited(apb->dev, + "APB-bus fault %d: Slave access timeout at 0x%08x\n", + atomic_inc_return(&apb->count), + addr); + + /* + * Print backtrace on each CPU. This might be pointless if the fault + * has happened on the same CPU as the IRQ handler is executed or + * the other core proceeded further execution despite the error. + * But if it's not, by looking at the trace we would get straight to + * the cause of the problem. + */ + trigger_all_cpu_backtrace(); + + regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, 0); + + return IRQ_HANDLED; +} + +static void bt1_apb_clear_data(void *data) +{ + struct bt1_apb *apb = data; + struct platform_device *pdev = to_platform_device(apb->dev); + + platform_set_drvdata(pdev, NULL); +} + +static struct bt1_apb *bt1_apb_create_data(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct bt1_apb *apb; + int ret; + + apb = devm_kzalloc(dev, sizeof(*apb), GFP_KERNEL); + if (!apb) + return ERR_PTR(-ENOMEM); + + ret = devm_add_action(dev, bt1_apb_clear_data, apb); + if (ret) { + dev_err(dev, "Can't add APB EHB data clear action\n"); + return ERR_PTR(ret); + } + + apb->dev = dev; + atomic_set(&apb->count, 0); + platform_set_drvdata(pdev, apb); + + return apb; +} + +static int bt1_apb_request_regs(struct bt1_apb *apb) +{ + struct platform_device *pdev = to_platform_device(apb->dev); + void __iomem *regs; + + regs = devm_platform_ioremap_resource_byname(pdev, "ehb"); + if (IS_ERR(regs)) { + dev_err(apb->dev, "Couldn't map APB EHB registers\n"); + return PTR_ERR(regs); + } + + apb->regs = devm_regmap_init_mmio(apb->dev, regs, &bt1_apb_regmap_cfg); + if (IS_ERR(apb->regs)) { + dev_err(apb->dev, "Couldn't create APB EHB regmap\n"); + return PTR_ERR(apb->regs); + } + + apb->res = devm_platform_ioremap_resource_byname(pdev, "nodev"); + if (IS_ERR(apb->res)) { + dev_err(apb->dev, "Couldn't map reserved region\n"); + return PTR_ERR(apb->res); + } + + return 0; +} + +static int bt1_apb_request_rst(struct bt1_apb *apb) +{ + int ret; + + apb->prst = devm_reset_control_get_optional_exclusive(apb->dev, "prst"); + if (IS_ERR(apb->prst)) { + dev_warn(apb->dev, "Couldn't get reset control line\n"); + return PTR_ERR(apb->prst); + } + + ret = reset_control_deassert(apb->prst); + if (ret) + dev_err(apb->dev, "Failed to deassert the reset line\n"); + + return ret; +} + +static void bt1_apb_disable_clk(void *data) +{ + struct bt1_apb *apb = data; + + clk_disable_unprepare(apb->pclk); +} + +static int bt1_apb_request_clk(struct bt1_apb *apb) +{ + int ret; + + apb->pclk = devm_clk_get(apb->dev, "pclk"); + if (IS_ERR(apb->pclk)) { + dev_err(apb->dev, "Couldn't get APB clock descriptor\n"); + return PTR_ERR(apb->pclk); + } + + ret = clk_prepare_enable(apb->pclk); + if (ret) { + dev_err(apb->dev, "Couldn't enable the APB clock\n"); + return ret; + } + + ret = devm_add_action_or_reset(apb->dev, bt1_apb_disable_clk, apb); + if (ret) { + dev_err(apb->dev, "Can't add APB EHB clocks disable action\n"); + return ret; + } + + apb->rate = clk_get_rate(apb->pclk); + if (!apb->rate) { + dev_err(apb->dev, "Invalid clock rate\n"); + return -EINVAL; + } + + return 0; +} + +static void bt1_apb_clear_irq(void *data) +{ + struct bt1_apb *apb = data; + + regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_MASK, 0); +} + +static int bt1_apb_request_irq(struct bt1_apb *apb) +{ + struct platform_device *pdev = to_platform_device(apb->dev); + int ret; + + apb->irq = platform_get_irq(pdev, 0); + if (apb->irq < 0) + return apb->irq; + + ret = devm_request_irq(apb->dev, apb->irq, bt1_apb_isr, IRQF_SHARED, + "bt1-apb", apb); + if (ret) { + dev_err(apb->dev, "Couldn't request APB EHB IRQ\n"); + return ret; + } + + ret = devm_add_action(apb->dev, bt1_apb_clear_irq, apb); + if (ret) { + dev_err(apb->dev, "Can't add APB EHB IRQs clear action\n"); + return ret; + } + + /* Unmask IRQ and clear it' pending flag. */ + regmap_update_bits(apb->regs, APB_EHB_ISR, + APB_EHB_ISR_PENDING | APB_EHB_ISR_MASK, + APB_EHB_ISR_MASK); + + return 0; +} + +static ssize_t count_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct bt1_apb *apb = dev_get_drvdata(dev); + + return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&apb->count)); +} +static DEVICE_ATTR_RO(count); + +static ssize_t timeout_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct bt1_apb *apb = dev_get_drvdata(dev); + unsigned long timeout; + int ret; + u32 n; + + ret = regmap_read(apb->regs, APB_EHB_TIMEOUT, &n); + if (ret) + return ret; + + timeout = bt1_apb_n_to_timeout_us(apb, n); + + return scnprintf(buf, PAGE_SIZE, "%lu\n", timeout); +} + +static ssize_t timeout_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct bt1_apb *apb = dev_get_drvdata(dev); + unsigned long timeout; + int ret; + u32 n; + + if (kstrtoul(buf, 0, &timeout) < 0) + return -EINVAL; + + n = bt1_apb_timeout_to_n_us(apb, timeout); + n = clamp(n, APB_EHB_TIMEOUT_MIN, APB_EHB_TIMEOUT_MAX); + + ret = regmap_write(apb->regs, APB_EHB_TIMEOUT, n); + + return ret ?: count; +} +static DEVICE_ATTR_RW(timeout); + +static ssize_t inject_error_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + return scnprintf(buf, PAGE_SIZE, "Error injection: nodev irq\n"); +} + +static ssize_t inject_error_store(struct device *dev, + struct device_attribute *attr, + const char *data, size_t count) +{ + struct bt1_apb *apb = dev_get_drvdata(dev); + + /* + * Either dummy read from the unmapped address in the APB IO area + * or manually set the IRQ status. + */ + if (!strncmp(data, "nodev", 5)) + readl(apb->res); + else if (!strncmp(data, "irq", 3)) + regmap_update_bits(apb->regs, APB_EHB_ISR, APB_EHB_ISR_PENDING, + APB_EHB_ISR_PENDING); + else + return -EINVAL; + + return count; +} +static DEVICE_ATTR_RW(inject_error); + +static struct attribute *bt1_apb_sysfs_attrs[] = { + &dev_attr_count.attr, + &dev_attr_timeout.attr, + &dev_attr_inject_error.attr, + NULL +}; +ATTRIBUTE_GROUPS(bt1_apb_sysfs); + +static void bt1_apb_remove_sysfs(void *data) +{ + struct bt1_apb *apb = data; + + device_remove_groups(apb->dev, bt1_apb_sysfs_groups); +} + +static int bt1_apb_init_sysfs(struct bt1_apb *apb) +{ + int ret; + + ret = device_add_groups(apb->dev, bt1_apb_sysfs_groups); + if (ret) { + dev_err(apb->dev, "Failed to create EHB APB sysfs nodes\n"); + return ret; + } + + ret = devm_add_action_or_reset(apb->dev, bt1_apb_remove_sysfs, apb); + if (ret) + dev_err(apb->dev, "Can't add APB EHB sysfs remove action\n"); + + return ret; +} + +static int bt1_apb_probe(struct platform_device *pdev) +{ + struct bt1_apb *apb; + int ret; + + apb = bt1_apb_create_data(pdev); + if (IS_ERR(apb)) + return PTR_ERR(apb); + + ret = bt1_apb_request_regs(apb); + if (ret) + return ret; + + ret = bt1_apb_request_rst(apb); + if (ret) + return ret; + + ret = bt1_apb_request_clk(apb); + if (ret) + return ret; + + ret = bt1_apb_request_irq(apb); + if (ret) + return ret; + + ret = bt1_apb_init_sysfs(apb); + if (ret) + return ret; + + return 0; +} + +static const struct of_device_id bt1_apb_of_match[] = { + { .compatible = "baikal,bt1-apb" }, + { } +}; +MODULE_DEVICE_TABLE(of, bt1_apb_of_match); + +static struct platform_driver bt1_apb_driver = { + .probe = bt1_apb_probe, + .driver = { + .name = "bt1-apb", + .of_match_table = bt1_apb_of_match + } +}; +module_platform_driver(bt1_apb_driver); + +MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>"); +MODULE_DESCRIPTION("Baikal-T1 APB-bus driver"); +MODULE_LICENSE("GPL v2"); |