/* * Helpers for controlling modem lines via GPIO * * Copyright (C) 2014 Paratronic S.A. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #include #include #include #include #include #include #include #include "serial_mctrl_gpio.h" struct mctrl_gpios { struct uart_port *port; struct gpio_desc *gpio[UART_GPIO_MAX]; int irq[UART_GPIO_MAX]; unsigned int mctrl_prev; bool mctrl_on; }; static const struct { const char *name; unsigned int mctrl; bool dir_out; } mctrl_gpios_desc[UART_GPIO_MAX] = { { "cts", TIOCM_CTS, false, }, { "dsr", TIOCM_DSR, false, }, { "dcd", TIOCM_CD, false, }, { "rng", TIOCM_RNG, false, }, { "rts", TIOCM_RTS, true, }, { "dtr", TIOCM_DTR, true, }, }; void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl) { enum mctrl_gpio_idx i; struct gpio_desc *desc_array[UART_GPIO_MAX]; int value_array[UART_GPIO_MAX]; unsigned int count = 0; if (gpios == NULL) return; for (i = 0; i < UART_GPIO_MAX; i++) if (gpios->gpio[i] && mctrl_gpios_desc[i].dir_out) { desc_array[count] = gpios->gpio[i]; value_array[count] = !!(mctrl & mctrl_gpios_desc[i].mctrl); count++; } gpiod_set_array_value(count, desc_array, value_array); } EXPORT_SYMBOL_GPL(mctrl_gpio_set); struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios, enum mctrl_gpio_idx gidx) { return gpios->gpio[gidx]; } EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod); unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl) { enum mctrl_gpio_idx i; if (gpios == NULL) return *mctrl; for (i = 0; i < UART_GPIO_MAX; i++) { if (gpios->gpio[i] && !mctrl_gpios_desc[i].dir_out) { if (gpiod_get_value(gpios->gpio[i])) *mctrl |= mctrl_gpios_desc[i].mctrl; else *mctrl &= ~mctrl_gpios_desc[i].mctrl; } } return *mctrl; } EXPORT_SYMBOL_GPL(mctrl_gpio_get); unsigned int mctrl_gpio_get_outputs(struct mctrl_gpios *gpios, unsigned int *mctrl) { enum mctrl_gpio_idx i; if (gpios == NULL) return *mctrl; for (i = 0; i < UART_GPIO_MAX; i++) { if (gpios->gpio[i] && mctrl_gpios_desc[i].dir_out) { if (gpiod_get_value(gpios->gpio[i])) *mctrl |= mctrl_gpios_desc[i].mctrl; else *mctrl &= ~mctrl_gpios_desc[i].mctrl; } } return *mctrl; } EXPORT_SYMBOL_GPL(mctrl_gpio_get_outputs); struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx) { struct mctrl_gpios *gpios; enum mctrl_gpio_idx i; gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL); if (!gpios) return ERR_PTR(-ENOMEM); for (i = 0; i < UART_GPIO_MAX; i++) { enum gpiod_flags flags; if (mctrl_gpios_desc[i].dir_out) flags = GPIOD_OUT_LOW; else flags = GPIOD_IN; gpios->gpio[i] = devm_gpiod_get_index_optional(dev, mctrl_gpios_desc[i].name, idx, flags); if (IS_ERR(gpios->gpio[i])) return ERR_CAST(gpios->gpio[i]); } return gpios; } EXPORT_SYMBOL_GPL(mctrl_gpio_init_noauto); #define MCTRL_ANY_DELTA (TIOCM_RI | TIOCM_DSR | TIOCM_CD | TIOCM_CTS) static irqreturn_t mctrl_gpio_irq_handle(int irq, void *context) { struct mctrl_gpios *gpios = context; struct uart_port *port = gpios->port; u32 mctrl = gpios->mctrl_prev; u32 mctrl_diff; unsigned long flags; mctrl_gpio_get(gpios, &mctrl); spin_lock_irqsave(&port->lock, flags); mctrl_diff = mctrl ^ gpios->mctrl_prev; gpios->mctrl_prev = mctrl; if (mctrl_diff & MCTRL_ANY_DELTA && port->state != NULL) { if ((mctrl_diff & mctrl) & TIOCM_RI) port->icount.rng++; if ((mctrl_diff & mctrl) & TIOCM_DSR) port->icount.dsr++; if (mctrl_diff & TIOCM_CD) uart_handle_dcd_change(port, mctrl & TIOCM_CD); if (mctrl_diff & TIOCM_CTS) uart_handle_cts_change(port, mctrl & TIOCM_CTS); wake_up_interruptible(&port->state->port.delta_msr_wait); } spin_unlock_irqrestore(&port->lock, flags); return IRQ_HANDLED; } struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx) { struct mctrl_gpios *gpios; enum mctrl_gpio_idx i; gpios = mctrl_gpio_init_noauto(port->dev, idx); if (IS_ERR(gpios)) return gpios; gpios->port = port; for (i = 0; i < UART_GPIO_MAX; ++i) { int ret; if (!gpios->gpio[i] || mctrl_gpios_desc[i].dir_out) continue; ret = gpiod_to_irq(gpios->gpio[i]); if (ret <= 0) { dev_err(port->dev, "failed to find corresponding irq for %s (idx=%d, err=%d)\n", mctrl_gpios_desc[i].name, idx, ret); return ERR_PTR(ret); } gpios->irq[i] = ret; /* irqs should only be enabled in .enable_ms */ irq_set_status_flags(gpios->irq[i], IRQ_NOAUTOEN); ret = devm_request_irq(port->dev, gpios->irq[i], mctrl_gpio_irq_handle, IRQ_TYPE_EDGE_BOTH, dev_name(port->dev), gpios); if (ret) { /* alternatively implement polling */ dev_err(port->dev, "failed to request irq for %s (idx=%d, err=%d)\n", mctrl_gpios_desc[i].name, idx, ret); return ERR_PTR(ret); } } return gpios; } EXPORT_SYMBOL_GPL(mctrl_gpio_init); void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios) { enum mctrl_gpio_idx i; if (gpios == NULL) return; for (i = 0; i < UART_GPIO_MAX; i++) { if (gpios->irq[i]) devm_free_irq(gpios->port->dev, gpios->irq[i], gpios); if (gpios->gpio[i]) devm_gpiod_put(dev, gpios->gpio[i]); } devm_kfree(dev, gpios); } EXPORT_SYMBOL_GPL(mctrl_gpio_free); void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios) { enum mctrl_gpio_idx i; if (gpios == NULL) return; /* .enable_ms may be called multiple times */ if (gpios->mctrl_on) return; gpios->mctrl_on = true; /* get initial status of modem lines GPIOs */ mctrl_gpio_get(gpios, &gpios->mctrl_prev); for (i = 0; i < UART_GPIO_MAX; ++i) { if (!gpios->irq[i]) continue; enable_irq(gpios->irq[i]); } } EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms); void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios) { enum mctrl_gpio_idx i; if (gpios == NULL) return; if (!gpios->mctrl_on) return; gpios->mctrl_on = false; for (i = 0; i < UART_GPIO_MAX; ++i) { if (!gpios->irq[i]) continue; disable_irq(gpios->irq[i]); } } EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms); MODULE_LICENSE("GPL"); al timing variation, cache behavior, etc). At the very least, this plugin is a much more comprehensive example for how to manipulate kernel code using the gcc plugin internals. The need for very-early boot entropy tends to be very architecture or system design specific, so this plugin is more suited for those sorts of special cases. The existing kernel RNG already attempts to extract entropy from reliable runtime variation, but this plugin takes the idea to a logical extreme by permuting a global variable based on any variation in code execution (e.g. a different value (and permutation function) is used to permute the global based on loop count, case statement, if/then/else branching, etc). To do this, the plugin starts by inserting a local variable in every marked function. The plugin then adds logic so that the value of this variable is modified by randomly chosen operations (add, xor and rol) and random values (gcc generates separate static values for each location at compile time and also injects the stack pointer at runtime). The resulting value depends on the control flow path (e.g., loops and branches taken). Before the function returns, the plugin mixes this local variable into the latent_entropy global variable. The value of this global variable is added to the kernel entropy pool in do_one_initcall() and _do_fork(), though it does not credit any bytes of entropy to the pool; the contents of the global are just used to mix the pool. Additionally, the plugin can pre-initialize arrays with build-time random contents, so that two different kernel builds running on identical hardware will not have the same starting values. Signed-off-by: Emese Revfy <re.emese@gmail.com> [kees: expanded commit message and code comments] Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'include/xen/interface')