[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH 3/4] xen/arm: pl011: Use correct accessors
At the moment, we use 32-bit only accessors (i.e. readl/writel) to match the SBSA v2.x requirement. This should not be the default case for normal PL011 where accesses shall be 8/16-bit (max register size is 16-bit). There are however implementations of this UART that can only handle 32-bit MMIO. This is advertised by dt property "reg-io-width" set to 4. Introduce new struct pl011 member mmio32 and replace pl011_{read/write} macros with static inline helpers that use 32-bit or 16-bit accessors (largest-common not to end up using different ones depending on the actual register size) according to mmio32 value. By default this property is set to false, unless: - reg-io-width is specified with value 4, - SBSA UART is in use. For now, no changes done for ACPI due to lack of testing possibilities (i.e. current behavior maintained resulting in 32-bit accesses). Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx> --- xen/drivers/char/pl011.c | 53 +++++++++++++++++++++++++++++++++++----- 1 file changed, 47 insertions(+), 6 deletions(-) diff --git a/xen/drivers/char/pl011.c b/xen/drivers/char/pl011.c index 052a6512515c..403b1ac06551 100644 --- a/xen/drivers/char/pl011.c +++ b/xen/drivers/char/pl011.c @@ -41,6 +41,7 @@ static struct pl011 { /* unsigned int timeout_ms; */ /* bool_t probing, intr_works; */ bool sbsa; /* ARM SBSA generic interface */ + bool mmio32; /* 32-bit only MMIO */ } pl011_com = {0}; /* These parity settings can be ORed directly into the LCR. */ @@ -50,9 +51,30 @@ static struct pl011 { #define PARITY_MARK (PEN|SPS) #define PARITY_SPACE (PEN|EPS|SPS) -/* SBSA v2.x document requires, all reads/writes must be 32-bit accesses */ -#define pl011_read(uart, off) readl((uart)->regs + (off)) -#define pl011_write(uart, off,val) writel((val), (uart)->regs + (off)) +/* + * By default, PL011 accesses shall be done using 8/16-bit accessors to + * support legacy devices that cannot cope with 32-bit. On the other hand, + * there are implementations of PL011 that can only handle 32-bit MMIO. Also, + * SBSA v2.x requires 32-bit accesses. Note that for default case, we use + * largest-common accessors (i.e. 16-bit) not to end up using different ones + * depending on the actual register size. + */ +static inline void +pl011_write(struct pl011 *uart, unsigned int offset, unsigned int val) +{ + if ( uart->mmio32 ) + writel(val, uart->regs + offset); + else + writew(val, uart->regs + offset); +} + +static inline unsigned int pl011_read(struct pl011 *uart, unsigned int offset) +{ + if ( uart->mmio32 ) + return readl(uart->regs + offset); + + return readw(uart->regs + offset); +} static unsigned int pl011_intr_status(struct pl011 *uart) { @@ -222,7 +244,8 @@ static struct uart_driver __read_mostly pl011_driver = { .vuart_info = pl011_vuart, }; -static int __init pl011_uart_init(int irq, paddr_t addr, paddr_t size, bool sbsa) +static int __init +pl011_uart_init(int irq, paddr_t addr, paddr_t size, bool sbsa, bool mmio32) { struct pl011 *uart; @@ -233,6 +256,9 @@ static int __init pl011_uart_init(int irq, paddr_t addr, paddr_t size, bool sbsa uart->stop_bits = 1; uart->sbsa = sbsa; + /* Set 32-bit MMIO also for SBSA since v2.x requires it */ + uart->mmio32 = (mmio32 || sbsa); + uart->regs = ioremap_nocache(addr, size); if ( !uart->regs ) { @@ -259,6 +285,8 @@ static int __init pl011_dt_uart_init(struct dt_device_node *dev, const char *config = data; int res; paddr_t addr, size; + uint32_t io_width; + bool mmio32 = false; if ( strcmp(config, "") ) { @@ -280,7 +308,19 @@ static int __init pl011_dt_uart_init(struct dt_device_node *dev, return -EINVAL; } - res = pl011_uart_init(res, addr, size, false); + /* See linux Documentation/devicetree/bindings/serial/pl011.yaml */ + if ( dt_property_read_u32(dev, "reg-io-width", &io_width) ) + { + if ( io_width == 4 ) + mmio32 = true; + else if ( io_width != 1 ) + { + printk("pl011: Unsupported reg-io-width (%"PRIu32")\n", io_width); + return -EINVAL; + } + } + + res = pl011_uart_init(res, addr, size, false, mmio32); if ( res < 0 ) { printk("pl011: Unable to initialize\n"); @@ -328,8 +368,9 @@ static int __init pl011_acpi_uart_init(const void *data) /* trigger/polarity information is not available in spcr */ irq_set_type(spcr->interrupt, IRQ_TYPE_LEVEL_HIGH); + /* TODO - mmio32 proper handling (for now set to true) */ res = pl011_uart_init(spcr->interrupt, spcr->serial_port.address, - PAGE_SIZE, sbsa); + PAGE_SIZE, sbsa, true); if ( res < 0 ) { printk("pl011: Unable to initialize\n"); -- 2.25.1
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