6.17-stable review patch. If anyone has any objections, please let me know.
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From: Viken Dadhaniya viken.dadhaniya@oss.qualcomm.com
[ Upstream commit fc6a5b540c02d1ec624e4599f45a17f2941a5c00 ]
GENI UART driver currently supports only non-DFS (Dynamic Frequency Scaling) mode for source frequency selection. However, to operate correctly in DFS mode, the GENI SCLK register must be programmed with the appropriate DFS index. Failing to do so can result in incorrect frequency selection
Add support for Dynamic Frequency Scaling (DFS) mode in the GENI UART driver by configuring the GENI_CLK_SEL register with the appropriate DFS index. This ensures correct frequency selection when operating in DFS mode.
Replace the UART driver-specific logic for clock selection with the GENI common driver function to obtain the desired frequency and corresponding clock index. This improves maintainability and consistency across GENI-based drivers.
Signed-off-by: Viken Dadhaniya viken.dadhaniya@oss.qualcomm.com Link: https://lore.kernel.org/r/20250903063136.3015237-1-viken.dadhaniya@oss.qualc... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/qcom_geni_serial.c | 92 ++++++--------------------- 1 file changed, 21 insertions(+), 71 deletions(-)
diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c index 81f385d900d06..ff401e331f1bb 100644 --- a/drivers/tty/serial/qcom_geni_serial.c +++ b/drivers/tty/serial/qcom_geni_serial.c @@ -1,5 +1,8 @@ // SPDX-License-Identifier: GPL-2.0 -// Copyright (c) 2017-2018, The Linux foundation. All rights reserved. +/* + * Copyright (c) 2017-2018, The Linux foundation. All rights reserved. + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. + */
/* Disable MMIO tracing to prevent excessive logging of unwanted MMIO traces */ #define __DISABLE_TRACE_MMIO__ @@ -1253,75 +1256,15 @@ static int qcom_geni_serial_startup(struct uart_port *uport) return 0; }
-static unsigned long find_clk_rate_in_tol(struct clk *clk, unsigned int desired_clk, - unsigned int *clk_div, unsigned int percent_tol) -{ - unsigned long freq; - unsigned long div, maxdiv; - u64 mult; - unsigned long offset, abs_tol, achieved; - - abs_tol = div_u64((u64)desired_clk * percent_tol, 100); - maxdiv = CLK_DIV_MSK >> CLK_DIV_SHFT; - div = 1; - while (div <= maxdiv) { - mult = (u64)div * desired_clk; - if (mult != (unsigned long)mult) - break; - - offset = div * abs_tol; - freq = clk_round_rate(clk, mult - offset); - - /* Can only get lower if we're done */ - if (freq < mult - offset) - break; - - /* - * Re-calculate div in case rounding skipped rates but we - * ended up at a good one, then check for a match. - */ - div = DIV_ROUND_CLOSEST(freq, desired_clk); - achieved = DIV_ROUND_CLOSEST(freq, div); - if (achieved <= desired_clk + abs_tol && - achieved >= desired_clk - abs_tol) { - *clk_div = div; - return freq; - } - - div = DIV_ROUND_UP(freq, desired_clk); - } - - return 0; -} - -static unsigned long get_clk_div_rate(struct clk *clk, unsigned int baud, - unsigned int sampling_rate, unsigned int *clk_div) -{ - unsigned long ser_clk; - unsigned long desired_clk; - - desired_clk = baud * sampling_rate; - if (!desired_clk) - return 0; - - /* - * try to find a clock rate within 2% tolerance, then within 5% - */ - ser_clk = find_clk_rate_in_tol(clk, desired_clk, clk_div, 2); - if (!ser_clk) - ser_clk = find_clk_rate_in_tol(clk, desired_clk, clk_div, 5); - - return ser_clk; -} - static int geni_serial_set_rate(struct uart_port *uport, unsigned int baud) { struct qcom_geni_serial_port *port = to_dev_port(uport); unsigned long clk_rate; - unsigned int avg_bw_core; + unsigned int avg_bw_core, clk_idx; unsigned int clk_div; u32 ver, sampling_rate; u32 ser_clk_cfg; + int ret;
sampling_rate = UART_OVERSAMPLING; /* Sampling rate is halved for IP versions >= 2.5 */ @@ -1329,17 +1272,22 @@ static int geni_serial_set_rate(struct uart_port *uport, unsigned int baud) if (ver >= QUP_SE_VERSION_2_5) sampling_rate /= 2;
- clk_rate = get_clk_div_rate(port->se.clk, baud, - sampling_rate, &clk_div); - if (!clk_rate) { - dev_err(port->se.dev, - "Couldn't find suitable clock rate for %u\n", - baud * sampling_rate); + ret = geni_se_clk_freq_match(&port->se, baud * sampling_rate, &clk_idx, &clk_rate, false); + if (ret) { + dev_err(port->se.dev, "Failed to find src clk for baud rate: %d ret: %d\n", + baud, ret); + return ret; + } + + clk_div = DIV_ROUND_UP(clk_rate, baud * sampling_rate); + /* Check if calculated divider exceeds maximum allowed value */ + if (clk_div > (CLK_DIV_MSK >> CLK_DIV_SHFT)) { + dev_err(port->se.dev, "Calculated clock divider %u exceeds maximum\n", clk_div); return -EINVAL; }
- dev_dbg(port->se.dev, "desired_rate = %u, clk_rate = %lu, clk_div = %u\n", - baud * sampling_rate, clk_rate, clk_div); + dev_dbg(port->se.dev, "desired_rate = %u, clk_rate = %lu, clk_div = %u\n, clk_idx = %u\n", + baud * sampling_rate, clk_rate, clk_div, clk_idx);
uport->uartclk = clk_rate; port->clk_rate = clk_rate; @@ -1359,6 +1307,8 @@ static int geni_serial_set_rate(struct uart_port *uport, unsigned int baud)
writel(ser_clk_cfg, uport->membase + GENI_SER_M_CLK_CFG); writel(ser_clk_cfg, uport->membase + GENI_SER_S_CLK_CFG); + /* Configure clock selection register with the selected clock index */ + writel(clk_idx & CLK_SEL_MSK, uport->membase + SE_GENI_CLK_SEL); return 0; }