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drivers/serial: ns16550: Add high speed baud rate support for IT8XXX2

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Add the support of high speed baud rate 230.4k and 460.8k
for IT8XXX2 of ITE.

Signed-off-by: Tim Lin <tim2.lin@ite.corp-partner.google.com>
This commit is contained in:
Tim Lin 2023-09-25 09:16:50 +08:00 • committed by Carles Cufí
commit 0bb77191c0
3 changed files with 73 additions and 7 deletions
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1
drivers/serial/Kconfig.it8xxx2
View file

@ -4,6 +4,7 @@
config UART_ITE_IT8XXX2
bool "ITE IT8XXX2 UART driver"
default y
select UART_NS16550_ITE_HIGH_SPEED_BUADRATE
depends on DT_HAS_ITE_IT8XXX2_UART_ENABLED
help
IT8XXX2 uses shared ns16550.c driver which does not

6
drivers/serial/Kconfig.ns16550
View file

@ -77,6 +77,12 @@ config UART_NS16550_TI_K3
Texas Instruments K3 SoCs by enabling a vendor specific extended register
set.
config UART_NS16550_ITE_HIGH_SPEED_BUADRATE
bool "IT8XXX2 specific baud rate configuration"
help
Enable IT8XXX2 specific baud rate configuration.
This applies to high-speed baud rate configuration.
menu "NS16550 Workarounds"
config UART_NS16550_WA_ISR_REENABLE_INTERRUPT

73
drivers/serial/uart_ns16550.c
View file

@ -242,6 +242,23 @@ BUILD_ASSERT(IS_ENABLED(CONFIG_PCIE), "NS16550(s) in DT need CONFIG_PCIE");
#define IIRC(dev) (((struct uart_ns16550_dev_data *)(dev)->data)->iir_cache)
#ifdef CONFIG_UART_NS16550_ITE_HIGH_SPEED_BUADRATE
/* Register definitions (ITE_IT8XXX2) */
#define REG_ECSPMR 0x08 /* EC Serial port mode reg */
/* Fields for ITE IT8XXX2 UART module */
#define ECSPMR_ECHS 0x02 /* EC high speed select */
/* IT8XXX2 UART high speed baud rate settings */
#define UART_BAUDRATE_115200 115200
#define UART_BAUDRATE_230400 230400
#define UART_BAUDRATE_460800 460800
#define IT8XXX2_230400_DIVISOR 32770
#define IT8XXX2_460800_DIVISOR 32769
#define ECSPMR(dev) (get_port(dev) + REG_ECSPMR * reg_interval(dev))
#endif
/* device config */
struct uart_ns16550_device_config {
union {
@ -395,6 +412,50 @@ static inline uintptr_t get_port(const struct device *dev)
return port;
}
static uint32_t get_uart_burdrate_divisor(const struct device *dev,
uint32_t baud_rate,
uint32_t pclk)
{
ARG_UNUSED(dev);
/*
* calculate baud rate divisor. a variant of
* (uint32_t)(pclk / (16.0 * baud_rate) + 0.5)
*/
return ((pclk + (baud_rate << 3)) / baud_rate) >> 4;
}
#ifdef CONFIG_UART_NS16550_ITE_HIGH_SPEED_BUADRATE
static uint32_t get_ite_uart_burdrate_divisor(const struct device *dev,
uint32_t baud_rate,
uint32_t pclk)
{
const struct uart_ns16550_device_config * const dev_cfg = dev->config;
uint32_t divisor = 0;
if (baud_rate > UART_BAUDRATE_115200) {
/* Baud rate divisor for high speed */
if (baud_rate == UART_BAUDRATE_230400) {
divisor = IT8XXX2_230400_DIVISOR;
} else if (baud_rate == UART_BAUDRATE_460800) {
divisor = IT8XXX2_460800_DIVISOR;
}
/*
* This bit indicates that the supported baud rate of
* UART1/UART2 can be up to 230.4k and 460.8k.
* Other bits are reserved and have no setting, so we
* directly write the ECSPMR register.
*/
ns16550_outbyte(dev_cfg, ECSPMR(dev), ECSPMR_ECHS);
} else {
divisor = get_uart_burdrate_divisor(dev, baud_rate, pclk);
/* Set ECSPMR register as default */
ns16550_outbyte(dev_cfg, ECSPMR(dev), 0);
}
return divisor;
}
#endif
static void set_baud_rate(const struct device *dev, uint32_t baud_rate, uint32_t pclk)
{
struct uart_ns16550_dev_data * const dev_data = dev->data;
@ -403,13 +464,11 @@ static void set_baud_rate(const struct device *dev, uint32_t baud_rate, uint32_t
uint8_t lcr_cache;
if ((baud_rate != 0U) && (pclk != 0U)) {
/*
* calculate baud rate divisor. a variant of
* (uint32_t)(pclk / (16.0 * baud_rate) + 0.5)
*/
divisor = ((pclk + (baud_rate << 3))
/ baud_rate) >> 4;
#ifdef CONFIG_UART_NS16550_ITE_HIGH_SPEED_BUADRATE
divisor = get_ite_uart_burdrate_divisor(dev, baud_rate, pclk);
#else
divisor = get_uart_burdrate_divisor(dev, baud_rate, pclk);
#endif
/* set the DLAB to access the baud rate divisor registers */
lcr_cache = ns16550_inbyte(dev_cfg, LCR(dev));
ns16550_outbyte(dev_cfg, LCR(dev), LCR_DLAB | lcr_cache);